US20110212179A1 - Micro-spherical porous biocompatible scaffolds and methods and apparatus for fabricating same - Google Patents

Micro-spherical porous biocompatible scaffolds and methods and apparatus for fabricating same Download PDF

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US20110212179A1
US20110212179A1 US13/126,456 US200913126456A US2011212179A1 US 20110212179 A1 US20110212179 A1 US 20110212179A1 US 200913126456 A US200913126456 A US 200913126456A US 2011212179 A1 US2011212179 A1 US 2011212179A1
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David Liu
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    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
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    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
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Definitions

  • bimodal porous polymer microspheres comprising macropores and micropores, and methods and apparatus for fabrication of such microspheres. Further provided herein are methods of using bimodal porous polymer microspheres.
  • Synthetic biocompatible porous scaffolds such as those disclosed in U.S. Pat. No. 6,337,198 (Levene et al.) may be used as frameworks for supporting cell growth and tissue regeneration.
  • Levene et al. disclose a method for fabricating a polymer-based scaffold with a bimodal pore distribution, where the larger pores are in the range of about 50 to about 500 microns and the smaller pores are less than 20 microns.
  • One drawback of the Levene et al. scaffold structure is its relatively large overall size.
  • the scaffolds disclosed in Levene et al. are fabricated using a mold (or dish) that forms a continuous polymer superstructure having the shape of the dish.
  • Levene et al. describe a dish of 8 mm in diameter and 2-3 mm thick. Scaffolds of this size must be surgically implanted at the target site and are not suitable for injection through catheter, needle or tubing, or for delivery to smaller environments within the body such as vascular environments.
  • Solid biocompatible spheres (without pores) are known in the prior art as a means of deliberately blocking blood flow to targeted tissues (such as cancerous tissues) in order to counteract the growth of such tissues.
  • targeted tissues such as cancerous tissues
  • embolization or embolotherapy See Liu et al., JVIR 2005, 16(7):911-935 and Chua et al., Clinical Radiology 2005, 60(1):116-122.
  • These solid spheres may also deliver radiation to provide radiation therapy to targeted tissues—see Salem et al., JVIR 2006, 17(8):1251-1278.
  • complete embolization in the target area may not be desirable since blood flow is required to provide oxygen.
  • porous scaffolding structures such as microspheres of a smaller size, suitable for injection through a catheter, needle or tubing, suitable for delivery to and suspension in microscopic environments within a living organism (in vivo), and capable of providing continued blood flow with minimal or optimized embolic effect.
  • a method for preparing a bimodal porous polymer particle comprising: (a) providing a homogeneous solution comprising a base polymer, a first solvent and a second solvent; (b) adding a macropore spacer material to the solution; (c) injecting droplets of the solution into a quenching device; (d) quenching droplets of the solution to solidify the base polymer into particles having macropores and micropores; (e) extracting substantially spherical particles from the quenching device, and optionally sieving the particles; and (f) optionally washing the macropore spacer material from the particles.
  • one or more of (a)-(f) is carried out at a temperature of less than 42° C. In one embodiment of the method, each of (a)-(f) are carried out at a temperature of less than 42° C.
  • particles made by these methods are also provided herein.
  • the particle is a microsphere, such as a substantially spherical microsphere. In other embodiments, the particle further comprises an additive.
  • a bimodal porous particle comprising a base polymer, wherein the particle comprises macropores having a diameter ranging from about 20 to about 500 microns and micropores having a diameter ranging from about 1 to about 70 microns, and wherein the microspheres have a diameter ranging from about 50 to about 1100 microns.
  • the particle is a microsphere, such as a substantially spherical microsphere.
  • the particle further comprises an additive.
  • the particle further comprises a cell.
  • a method of complete or partial embolization in a patient comprising administering to the patient the bimodal porous particle provided herein.
  • the particle provides or allows temporary or continued perfusion of the blood vessel, vein, artery, tissue or organ, e.g., about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, or about 95% as compared to the amount of perfusion in the absence of particle.
  • a method of treating or otherwise managing a cancer or tumor, or a symptom thereof, in a patient comprising administering a bimodal porous particle provided herein to a blood vessel, vein or artery of the patient that directly or indirectly supplies the cancer or tumor with blood.
  • the particle provides or allows temporary or continued perfusion of the cancer or tumor.
  • a method for delivering cells to a patient comprising administering a bimodal porous particle provided herein to the patient, wherein the bimodal porous particle comprises cells.
  • the cells are delivered to or otherwise contacted with a tissue or organ of the patient.
  • the particle provides or allows temporary or continued perfusion of the area where the cell is delivered.
  • a method for retaining cells in a tissue or organ of a patient comprising administering a bimodal porous particle provided herein to the patient, wherein the bimodal porous particle comprises cells, and contacting the cells with the tissue or organ.
  • the particle provides or allows temporary or continued perfusion of the area where the cell is delivered.
  • a method for engrafting cells in a tissue or organ of a patient comprising administering a bimodal porous particle provided herein to the patient, wherein the bimodal porous particle comprises cells, and contacting the cells with the tissue or organ.
  • the particle provides or allows temporary or continued perfusion of the area where the cell is delivered.
  • a method for tissue regeneration in a patient comprising administering a bimodal porous particle provided herein to the patient, wherein the bimodal porous particle comprises cells, wherein the cells are contacted with the tissue being regenerated.
  • the tissue is heart, lung, nervous, brain, liver or pancreas tissue.
  • the tissue is a blood vessel, vein or artery.
  • the tissue is a wound or other injured tissue.
  • the particle provides or allows temporary or continued perfusion of the area where the cell is delivered.
  • the particle is administered to the heart, lung, nervous system, brain, lung, liver or pancreas of the patient.
  • a method for islet cell transplantation in a patient comprising administering a bimodal porous particle provided herein to the patient, wherein the cell is an islet cell.
  • the particle provides or allows temporary or continued perfusion of the area where the cell is delivered.
  • a method for treating or otherwise managing diabetes, or a symptom thereof, in a patient comprising administering a bimodal porous particle provided herein to the patient, wherein the cell is an islet cell.
  • the islet cell produces insulin.
  • the particle is administered to the liver (e.g., a portal vein of the liver) of the patient.
  • the particle provides or allows temporary or continued perfusion of the area where the cell is delivered.
  • a method for intraarterial brachytherapy in a patient administering a bimodal porous particle provided herein to the patient.
  • the particle comprises an additive, such as a radioactive material.
  • the particle is administered to a cancer or tumor.
  • the particle provides or allows temporary or continued perfusion of the cancer or tumor.
  • the particle completely or partially embolizes a blood vessel, vein or artery of the patient that directly or indirectly supplies the cancer or tumor with blood.
  • a method for delivering an additive to a patient comprising administering a bimodal porous particle provided herein to the patient, wherein the particle comprises the additive.
  • the additive is a therapeutic agent or drug.
  • the additive is a tracer or imaging agent.
  • the additive is a diagnostic agent.
  • a method of prolonged and/or controlled delivery of an additive e.g., a therapeutic agent or drug in a patent, comprising administering a bimodal porous particle provided herein to the patient, wherein the particle comprises the additive.
  • the particle is administered to the patient by intraluminal, interstitial, subdermal, transdermal or subcutaneous administration.
  • a method of trapping, filtering or extracting cells from the blood of a patient comprising administering a bimodal porous particle provided herein to the patient, wherein the particle allows for perfusion through the particle, and wherein the particle traps, filters, attracts, promotes cell migration, or extracts the cells from the blood or adjacent tissue of the patient.
  • an apparatus for fabricating bimodal porous polymer particles comprising: (a) a storage vessel; (b) a quenching tower; (c) an injector comprising a nozzle, wherein the nozzle has a diameter ranging from about 5 to about 1100 microns in diameter; and wherein the vessel is connected to the injector; and (d) one or more microsieves.
  • the nozzle can be substituted by other means of providing laminar flow through an aperature, such as in established focused fluidics techniques.
  • a flow-focusing geometry integrated into a plannar microchannel can be used to substitute the nozzle.
  • the injector further comprises a chamber and a piston.
  • the storage vessel further comprises an agitator or mixer.
  • the storage vessel comprises a first solvent, a second solvent and a base polymer provided herein.
  • the apparatus further comprising a conduit attached to the storage vessel, wherein the conduit optionally comprises a micropore spacer material provided herein.
  • additive refers to a substance, molecule or material (e.g., bio-active material) a microsphere may carry, contain, be impregnated with, coated with, or bonded with.
  • an additive may be added to the base polymer during fabrication process.
  • additives include therapeutic agents, cells, cell differentiating and signaling materials, cell adhesion factors or promoters (e.g., selectins, collagen, gelatin, glucosaminoglycans, fibronectins, lectins, polycations, polylysine, chitosan and the like, or any other natural or synthetic biological cell adhesion agent), antibodies, blood clotting or anti-clotting agents, radioactive sources and chemotherapy materials.
  • therapeutic agents include therapeutic agents, cells, cell differentiating and signaling materials, cell adhesion factors or promoters (e.g., selectins, collagen, gelatin, glucosaminoglycans, fibronectins, lectins, polycations, polylysine
  • administer refers to the act of injecting or otherwise physically delivering a substance as it exists outside the body (e.g., la particle or microsphere provided herein) into a patient, such as by, but not limited to, pulmonary (e.g., inhalation), mucosal (e.g., intranasal), intradermal, intravenous, intraarterial, intrabiliary, intraocular, intraosseous, intramuscular delivery and/or any other method of physical delivery described herein or known in the art.
  • pulmonary e.g., inhalation
  • mucosal e.g., intranasal
  • intradermal intravenous, intraarterial, intrabiliary, intraocular, intraosseous, intramuscular delivery and/or any other method of physical delivery described herein or known in the art.
  • administration of the substance typically occurs after the onset of the disease or symptoms thereof.
  • administration of the substance typically occurs before the onset of the disease or symptoms thereof.
  • Such administration results in the delivered particles (e.g., a particle and/or additive provided herein) contacting the target area (e.g., a tissue or organ).
  • bimodal pore distribution refers to two different ranges of pore sizes (e.g., macropores versus micropores or large pores versus small pores) present in the porous polymer scaffolds or microspheres provided herein.
  • the size of the macropores in the bimodal pore distribution can be on the order of about 20 to about 500 microns and the micropores can be on the order of about 1 to about 70 microns.
  • the size of the macropores can be on the order of about 20 to about 200 microns and the micropores can be on the order of about 1 to about 40 microns.
  • the term “bimodal porous microspheres,” “bimodal porous polymeric microspheres” or “bimodal porous polymer microspheres” as used herein refers to polymeric microspheres comprising pores of bimodal size distribution.
  • bioabsorbable refers to the ability of a material to degrade, be metabolized by the body in vivo or be eliminated from the body.
  • biodegradable refers to a material or object (e.g., polymer, microsphere) that is capable of being absorbed by the body, chemically, physiologically, or by other biological means, over a period of time.
  • biocompatible refers to the property or ability of a material or object (e.g., polymer or microspheres) to be applied in vivo (e.g., to cells, tissues or organs) without eliciting significant immune responses, inflammation or other adverse responses unless otherwise intended.
  • a material or object e.g., polymer or microspheres
  • Cell adhesion promoter as used herein means any material that, because of their presence in or association with the microspheres, promotes or enhances the adhesiveness of cells to the surface of the microspheres. These materials are often proteins that are bound to the surface of the microspheres through covalent bonds of the proteins and the polymers.
  • an effective amount refers to the amount of a therapy (e.g., a microsphere or composition provided herein) which is sufficient to reduce and/or ameliorate the severity and/or duration of a given disease and/or a symptom related thereto.
  • a therapy e.g., a microsphere or composition provided herein
  • an effective amount of the particle is administered to the patient.
  • transplantation refers to a process by which transplanted cells are accepted by a host tissue, survive and persist in that environment, e.g., for a period of 24 hours or more. In certain embodiments, the transplanted stem cells further reproduce.
  • a first therapy can be administered before (e.g., 1 minute, 15 minutes, 30 minutes, 45 minutes, 1 hour, 2 hours, 4 hours, 6 hours, 12 hours, 24 hours, 48 hours, 72 hours, 96 hours, 1 week, 2 weeks, 3 weeks, 4 weeks, 5 weeks, 6 weeks, 8 weeks, or 12 weeks), concurrently, or after (e.g., 1 minute, 15 minutes, 30 minutes, 45 minutes, 1 hour, 2 hours, 4 hours, 6 hours, 12 hours, 24 hours, 48 hours, 72 hours, 96 hours, 1 week, 2 weeks, 3 weeks, 4 weeks, 5 weeks, 6 weeks, 8 weeks, or 12 weeks) the administration of a second therapy to a subject which had, has, or is susceptible to a given disease.
  • any additional therapy can be administered in any order with the other additional therapies.
  • the particles provided herein can be administered in combination with one or more therapies (e.g., therapies that are not the magnetically labeled cells that are currently administered to prevent, treat, manage, and/or ameliorate a given disease or other symptom related thereto).
  • therapies e.g., therapies that are not the magnetically labeled cells that are currently administered to prevent, treat, manage, and/or ameliorate a given disease or other symptom related thereto.
  • therapies that can be administered in combination with the particles provided herein include additives, such as analgesic agents, anesthetic agents, antibiotics, or immunomodulatory agents or any other agent listed in the U.S. Pharmacopoeia and/or Physician's Desk Reference.
  • injectable means capable of being administered, delivered or carried into the body via syringe, catheters, needles or other means for injecting or infusing the microspheres in a liquid medium.
  • the particles provided herein are injectable particles.
  • the terms “manage,” “managing,” and “management” refer to the beneficial effects that a subject derives from a therapy (e.g., microspheres provided herein), which does not result in a cure of the infection.
  • a subject is administered one or more therapies to “manage” a given disease or one or more symptoms related thereto, so as to prevent the progression or worsening of the disease.
  • microspheres refer to a polymer or combinations of polymers made into bodies of various sizes.
  • the microspheres as used herein can be in any shape, although they are often in substantially spherical shape. These structures of the microspheres may be generally spherical or spheroid in shape or bounded by imaginary spherical or spheroid shapes.
  • the microspheres may be sterilized by any method known in the art, for example, by irradiation, such as gamma or beta irradiation.
  • the microspheres provided herein may comprise other materials as described and defined herein.
  • microsphere represents a convenient description for the purposes of explanation of the compositions and methods provided herein, and that, in certain embodiments, the exemplary microspheres described herein are not necessarily limited to being precisely spherical in shape (e.g., are particles).
  • pharmaceutically acceptable means being approved by a regulatory agency of the Federal or a state government, or listed in the U.S. Pharmacopeia, European Pharmacopeia or other generally recognized pharmacopeia for use in animals, and more particularly in humans
  • polymer refers to a molecule consisting of multiple repetition of molecular units.
  • the polymer as used herein can be in any form of structure, for instance, linear or branched (e.g., a “multi-arm” or “star-shaped).
  • base polymer refers to a polymer which may be incorporated into a composition comprising, for example, a polymer and one or more additives.
  • copolymer refers to a polymer formed by a combination of two or more monomeric or polymeric species.
  • block copolymer refers to a copolymer composed of block macromolecules.
  • adjacent blocks in a block copolymer comprise units derived from different species of monomer or from the same species of monomer but with a different composition or sequence distribution of constitutional units.
  • polymer as used herein should not be limited to polymers in the strict chemical sense and that other suitable materials having the characteristics described herein may be used.
  • the terms “prevent,” “preventing,” and “prevention” refer to the total or partial inhibition of a given disease; the total or partial inhibition of the development or onset of disease progression of given disease, or a symptom related thereto in a subject; the total or partial inhibition of the progression of an given disease or a symptom related thereto.
  • tissue regeneration refers to the process of growing and/or developing new tissue.
  • tissue regeneration comprises activation and/or enhancement of cell proliferation.
  • tissue regeneration comprises activation and/or enhancement of cell migration.
  • transplanted cells are retained by a host tissue or organ, e.g., are accepted, survive and persist in that environment, e.g., for a period of minutes to hours. In certain embodiments, the transplanted cells further reproduce.
  • stem cells refers to cells that have the capacity to self-renew and to generate differentiated progeny.
  • the stem cells are mesenchymal stem cells.
  • a subject is a mammal such as a non-primate (e.g., cows, pigs, horses, cats, dogs, rats, rabbits, etc.) or a primate (e.g., monkey and human) comprising administration of particles as provided herein.
  • a primate e.g., monkey and human
  • the patient is in need of treatment or management of the disease or symptom thereof.
  • the subject is a human.
  • substantially spherical or “generally spherical” refers to a shape that is close to a perfect sphere, which is defined as a volume that presents the lowest external surface area. Specifically, “substantially spherical” as used herein means, when viewing any cross-section of the particle, the difference between the average major diameter and the average minor diameter is less than 20%. In some embodiments, the surfaces of the microspheres provided herein appear smooth under magnification of up to 1000 times.
  • therapeutic agent or “therapeutic drug” can be used interchangeably herein and refers to any therapeutically active substance that is delivered to a bodily conduit of a living being to produce a desired, usually beneficial, effect.
  • the term “therapy” refers to any protocol, method and/or agent that can be used in the management, treatment and/or amelioration of a given disease, or a symptom related thereto.
  • the terms “therapies” and “therapy” refer to a biological therapy, supportive therapy, and/or other therapies known to one of skill in the art, such as medical personnel, useful in the management or treatment of a given disease, or symptom related thereto.
  • tissue construction tissue generation
  • tissue engineering tissue engineering
  • tissue repair tissue repair
  • the tissues encompassed include, but are not limited to, muscle tissues, connective tissues, fats, and, nerve tissues.
  • tissue defects suitable for the treatment and management methods provided herein include, but not limited to, defects in a patient's heart, coronary vessels, blood vessels, spinal cord, bone, cartilage, tendon, ligament, breast, liver, gallbladder, bile duct, pancreas, intestinal tissues, urinary system, skin, hernia, and dental tissues.
  • treat refers to the reduction or amelioration of the progression, severity, and/or duration of a disease or a symptom thereof.
  • FIGS. 1A-1B depict an exemplary biocompatible porous microsphere (microsphere 20 ) according to particular embodiments provided herein.
  • FIG. 1A is a cross-sectional view of the biocompatible porous microsphere 20 .
  • FIG. 1B depicts a magnified view of a portion of a cross-section of microsphere 20 , illustrating its bimodal pore distribution.
  • FIG. 2 shows an apparatus (apparatus 50 ) for fabricating biocompatible porous microspheres (e.g., microsphere 20 ) according to a particular embodiment provided herein.
  • FIG. 3 is a flowchart illustrating the steps of an exemplary method (method 200 ) of fabricating biocompatible porous microspheres (e.g., microsphere 20 ) according to a particular embodiment provided herein.
  • biocompatible bimodal porous scaffolding structures e.g., particles, such a microspheres
  • the scaffold structures are fabricated using the surface tension of liquid material to provide generally spherical or spheroid shapes or to be bounded by imaginary spherical or spheroid shapes and are referred to herein as microspheres.
  • the microspheres are in a range of about 50 to about 1100 microns in diameter. In other embodiments, the microspheres are under about 500 microns in diameter. In still other embodiments, the microspheres are under about 300 microns in diameter. These diameters permit the microspheres to be delivered to target tissues in vivo via catheter, needle, tubing, or the like by various pathways including vascular, intraductal, transesophogeal, subcutaneous, subdermal, submucosal, transbronchial, or interstitial. In some embodiments, the size of the macropores in the bimodal pore distribution may be on the order of about 20 to about 500 microns and the micropores may be on the order of about 1 to about 70 microns.
  • the size of the macropores may be on the order of about 20 to about 200 microns and the micropores may be on the order of about 1 to about 40 microns.
  • the bimodal porous polymer microspheres further comprise an additive.
  • a bimodal porous polymer microsphere comprising macropores having a diameter ranging from about 20 to about 500 microns, or from about 20 to about 200 microns; and micropores having a diameter ranging from about 1 to about 70 microns or from about 1 to about 40 microns.
  • the wherein the microspheres have a diameter ranging from about 50 to about 1100 microns, from about 50 to about 500 microns, or from about 50 to about 300 microns.
  • FIG. 1A depicts an exemplary biocompatible porous microsphere 20 according to particular embodiments provided herein, as viewed from a cross-section taken through its center.
  • FIG. 1B depicts a magnified view of a portion of a cross-section of microsphere 20 , illustrating its bimodal pore distribution.
  • Microsphere 20 comprises a biocompatible base polymer or monomer 22 (referred to in this description as base polymer 22 ).
  • base polymer 22 may also be bioabsorbable and/or biodegradable. Examples of suitable base polymers 22 are described elsewhere herein.
  • the size of microsphere is in the range of about 50 to about 1100 microns in diameter to facilitate catheter-based delivery of microspheres 20 into target tissue beds by various pathways including vascular (arterial, venous, portal), intraductal (e.g. biliary tree), transesophageal, subcutaneous, subdermal, submucosal, transbronchial, or interstitial delivery.
  • vascular arterial, venous, portal
  • intraductal e.g. biliary tree
  • transesophageal subcutaneous, subdermal, submucosal, transbronchial, or interstitial delivery.
  • Other possible delivery mechanisms include injection via a needle or tubing and direct placement in, on or in a vicinity of the target tissue.
  • Other non-limiting examples of delivering microspheres are provided elsewhere herein.
  • Microspheres provided herein may be permeated with pores of various sizes and shapes.
  • microsphere ( 20 ) has a bimodal pore distribution, which includes relatively large pores (macropores) ( 24 ) and relatively small pores (micropores) ( 26 ).
  • micropores have diameters in a range of about 1 to about 70 microns and macropores have diameters in a range of about 20 to about 500 microns.
  • Such a bimodal pore distribution in comparison to a uniform pore distribution, tends to increase the overall porosity and surface area of microspheres, reduce the mass density of microspheres, and increase the number of interconnections between the pores in microspheres.
  • Bimodal pore distribution may permit improved blood flow dynamics through and around microspheres in vivo, reducing blood flow resistance, turbulence and pressure differentials caused by microspheres and thereby reducing perfusional gradients and the potential formation of blood clots (thrombogenesis). Similar improved flow dynamics may be produced in fluids other than blood. Bimodal distribution may also allow for site of sequestration of cells, enabling adhesion, fixation or differentiation in the lager pore, while maintaining perfusion through the microsphere via either macropores or micropores.
  • Macropores may provide sufficiently open space for the formation of functional tissue within the scaffold of microspheres while micropores can form channels between macropores to increase or otherwise optimize cell-to-cell contact or communication, diffusion of nutrients and oxygen to the cells, osmosis, and surface patterning to guide the cells.
  • Macropores may also serve as channels through which blood or other fluids may flow, and may potentially differentiate into a permanent conduit (such as an artificial blood vessel, bile duct or vein, for example).
  • the porosity of the bimodal pore distribution in particular microspheres may be designed to allow the specific gravity of microspheres to closely match (or to otherwise have a certain relationship (e.g., heavier or lighter)) than that of its target fluid suspension or target tissues.
  • the particles further comprise a cell adhesion promoter.
  • the particles comprises a gelatin.
  • the particles are crosslinked. In other embodiments, the particles are not crosslinked. In certain embodiments, the particles are sterile.
  • microspheres provided herein may comprise, in addition to the particles, other materials.
  • macropores and micropores of the microspheres provided herein can comprise, e.g., carry, contain, be impregnated with, coated with, or bonded with, various bioactive materials or other additives provided herein such as, but not limited to, therapeutic agents, cells, cell differentiating and signaling materials, cell adhesion factors (e.g., selectins), antibodies, blood clotting or anti-clotting agents, and chemotherapy materials.
  • additives are provided elsewhere herein.
  • Such material-carrying microspheres allow for the delivery and prolonged exposure of a selected therapy to a specific target tissue.
  • the sizes of macropores and micropores may be varied according to embodiments provided herein to allow for the carrying of additives of varying sizes.
  • a biocompatible porous particle e.g., a microsphere
  • the process involves preparing a homogeneous solution comprising a base polymer dissolved in a first solvent (in which the base polymer is soluble) and a second solvent in which the base polymer is insoluble, but which is miscible in the first solvent.
  • a homogeneous solution comprising a base polymer dissolved in a first solvent (in which the base polymer is soluble) and a second solvent in which the base polymer is insoluble, but which is miscible in the first solvent.
  • the homogeneous solution thus prepared is cast in a mold atop solid macropore spacer particles having suitable sizes.
  • the macropore spacer particles are not soluble in the first solvent, but may be water-soluble.
  • the resultant mixture is phase-separated by quenching at low temperature, resulting in crystallization of the first solvent while minimizing liquid-liquid demixing of the polymer solution.
  • a leaching process is then performed to remove the macropore spacers.
  • micropores can be created in the material by crystallization upon phase separation of the first solvent (i.e., the solvent in which the base polymer is soluble) and macropores are created by leaching which dissolves the macropore spacers.
  • the second solvent may be used to implement the leaching process.
  • FIG. 2 illustrates an apparatus ( 50 ) which may be used to fabricate microspheres 20 according to a particular embodiment provided herein.
  • FIG. 3 illustrates a block diagram of a particular embodiment of a method for fabricating microspheres 20 using apparatus 50 .
  • method 200 begins in block 202 , which involves preparing a homogeneous solution 54 by mixing base polymer 22 with a first solvent (in which the base polymer is soluble) and a second solvent in which the base polymer is insoluble, but which is miscible in the first solvent.
  • the first and second solvents are miscible, and can form a mixture in which the base polymer is soluble.
  • the ratio of the amounts of first and second solvents in solution 54 may be selected to permit the base polymer to be substantially fully dissolved and to permit solution 54 to be substantially homogeneous.
  • the volume ratio of the first solvent to the total volume of solvent is between about 1% to about 50% v/v, about 1% to about 40% v/v, about 2% to about 30% v/v or about 4% to about 25% v/v. In a specific embodiment, the volume ratio of the first solvent to the total volume of solvent is about 5% to about 15% v/v.
  • the polymer concentration in the solvent mixture is between about 0.1% to about 50% by weight, between about 1% to about 40%, or about 5% to about 23% by weight. In a specific embodiment, the polymer concentration in the solvent mixture is between about 10% to about 20% by weight.
  • the base polymer(s), the first and second solvents and macropore spacer material ( 68 ) can be selected from a variety of suitable materials.
  • solution 54 is provided in a storage vessel 52 .
  • the vessel 52 can comprise an agitator, a mixer or the like (not shown) to ensure that the base polymer 22 is substantially fully dissolved in solution 54 .
  • macropore spacer particles 68 may be combined with the solvent solution 54 in vessel 52 .
  • macropore spacer particles 68 may be separately added via conduit 66 as described below.
  • vessel 52 is in fluid communication with injector 60 via conduit 58 which may comprise valves 56 and/or 62 .
  • other suitable devices may be used to provide solution 54 to injector 60 .
  • injector 60 comprises a chamber 61 into which solution 54 is provided and a pressure providing piston 64 .
  • piston 64 may be actuated by any suitable means to reduce the volume of chamber 61 and to thereby apply pressure to fluids contained therein as such fluids are directed toward outlet conduit 70 and nozzle 72 .
  • method 200 then proceeds to block 204 , which involves adding macropore spacer particles 68 to injector 60 via conduit 66 .
  • macropore spacers 68 may be carried in a small amount of one of the first or second solvents to facilitate addition of spacers 68 to solution 54 .
  • macropore spacers 68 may be admixed with the first solvent to allow it to be more easily injectable into solution 54 .
  • macropore spacers 68 are added to solution 54 in outlet conduit 70 (i.e. as close as reasonably possible to nozzle 72 ) and as temporally close as possible to injection of solution 54 into tower 80 via nozzle 72 .
  • macropore spacers 68 is added in such a manner that they become reasonably evenly dispersed within solution 54 in outlet conduit 70 .
  • other suitable mechanisms may be used to add macropore spacers 68 to solution 54 .
  • Such other suitable mechanisms may involve adding macropore spacers 68 to solution 54 in injector 60 or in other locations (e.g., in vessel 52 ).
  • apparatus 50 may comprise a mechanism or device for controlling the size of injected macropore spacer particles 68 , such as by employing suitable sieves in conduit 66 or the like.
  • method 200 then proceeds to block 206 , which involves injecting the mixture of solution 54 and macropore spacers 68 from injector 60 into quenching tower 80 in a manner which creates droplets 84 A, 84 B (collectively, droplets 84 ) of the mixture of solution 54 and macropore spacers 68 in tower 80 .
  • droplets 84 are formed and injected from injector 60 into quenching tower 80 using a nozzle 72 .
  • droplets 84 are formed and injected from injector 60 into quenching tower 80 using a device that creates a fixed rate and aperature of laminar or nonlaminar dispersion into part 90 .
  • Nozzle 72 may comprise a one or more variable sized apertures 74 which may be varied to control the size of droplets 84 .
  • the size of droplets 84 created by nozzle 72 is on the order of about 5 to about 1100 microns in diameter. Suitable nozzles or similar devices are known to those skilled in the art.
  • droplets 84 may be created using other suitable configured mistifying devices located between injector 60 and quenching tower 80 .
  • the rate of injection of droplets 84 through nozzle 72 and into tower 80 may be controlled by adjusting nozzle 72 and/or by adjusting the pressure applied to piston 64 .
  • the rate of injection of droplets 84 into tower 80 should be controlled to facilitate quenching of droplets 84 as described herein.
  • method 200 then proceeds to block 208 , which involves rapidly freezing (i.e. quenching) droplets 84 as soon as possible after droplets 84 enter tower 80 .
  • quenching tower 80 may comprise or otherwise be provided with means (not explicitly shown) for controlling or otherwise regulating the temperature and pressure therein.
  • pressure and temperature regulation means are well known in the art and may include any suitable devices.
  • the temperature and pressure within quenching tower 80 are regulated to induce quenching of droplets 84 as soon as possible after droplets 84 enter tower 80 , as explained in more detail below.
  • quenching tower 80 is capable of supporting suitable pressures and temperatures for inducing rapid polymerization of base polymer 22 through phase change of the solvents from liquid to solid, before any significant dissociation of the liquids (e.g., liquid-liquid demixing of the first and second solvents) occurs in solution 54 .
  • tower 80 may be filled with a suitable non-reactive medium 82 for effecting a rapid temperature drop.
  • medium 82 of tower 80 may comprise liquid nitrogen or other suitable coolants.
  • medium 82 of tower 80 may consist of or comprise the second solvent.
  • the quenching of droplets 84 triggers crystallization of the first solvent and results in base polymer 22 solidifying out of solution (polymerizing).
  • base polymer 22 solidifies around macropore spacer particles 68 , forming impressions within solidified base polymer 22 that correspond to macropores 24 .
  • the phase change from liquid to solid also results in the formation of a network of micropores 26 within microsphere 20 .
  • the quenching in tower 80 causes the crystallization of the first solvent in the solution, which in turn triggers the polymerization of base polymer 22 and the formation of micropores 26 in the resulting microsphere 20 .
  • the second solvent which is immiscible with base polymer 22 but miscible with the first solvent acts as a nucleating agent that initiates the crystallization of the first solvent.
  • droplets 84 (which are initially suspended in medium 82 of tower 80 ) are generally spherical or globular shaped (subject to deformation forces, such as gravity, forces which may be applied by injector 60 and the like).
  • the result of generally spherical droplets 84 is that when droplets 84 are quenched in tower 80 , the resultant solidified base polymer 22 retains the generally spherical shape which (as explained further below) provides generally microspherically shaped structures 85 A, 85 B (collectively, microspheres 85 ).
  • droplets 84 provides a large surface area to volume ratio, which improves quenching speed in relation to prior art processes which involve quenching in dish-shaped molds. While not wishing to be bound by any theory, faster quenching speed minimizes liquid-liquid separation during cooling. Liquid-liquid demixing can significantly reduce the formation of micropores 26 and thereby impact the bimodal pore distribution.
  • tower 80 is vertically oriented, though in other embodiments tower 80 may be oriented in other directions.
  • the mass density of droplets 84 and/or microspheres 85 may be greater than or less than the mass density of medium 82 in which they are suspended.
  • droplets 84 A and/or microspheres 85 A that are less dense than medium 82 will tend to rise in direction 86 A.
  • droplets 84 B and/or microspheres 85 B that are more dense than medium 82 will tend to sink in direction 86 B.
  • method 200 then proceeds to block 210 , which involves extracting microspheres 85 from tower 80 .
  • the block 210 extraction is performed using microsieves 94 A, 94 B (collectively, microsieves 94 ).
  • microspheres 85 may be extracted from tower 80 by way of one or both of outlet channels 88 A, 88 B (collectively outlet channels 88 ) which respectively incorporate microsieves 94 A, 94 B.
  • One or more suitably configured pumps 90 A, 90 B may be used to circulate medium 82 carrying microspheres 85 around a loop from tower 80 , through output channels 88 , through microsieves 94 , and back into tower 80 through a return channel 106 .
  • Part 92 A is a narrow conduit, for example, tubing or other flexible substance that would allow for a continuous circuit of fluid flow to promote the movements of the microspheres into the sieve.
  • part 92 A is tubing that would be attached to part 90 A, which would be, for example, a roller pump, thermal pump or other mechanism to promote a flow of fluid through the circuit.
  • upper output channel 88 A is connected at or near the top of tower 80 to extract microspheres 85 A that rise within medium 82 and lower output channel 88 B is connected at or near the bottom of tower 80 to extract microspheres 85 B that sink within medium 82 .
  • apparatus 50 may comprise any suitable mechanism for circulating medium 82 through microsieves 94 and that embodiments of apparatus 50 are not limited to the particular circulation paths and pumping arrangements shown in FIG. 3 .
  • the use of a pair of output channels 88 is not necessary.
  • microspheres 85 may be forced through a single output channel and a corresponding microsieve by a suitably configured pump.
  • one of upper output channel 88 A or lower output channel 88 B may be operational and the other one of channels 88 may be shut off (e.g., by a suitably configured valve).
  • the one of channels 88 that may be selected for operation may depend on the expected mass density of microspheres 85 .
  • apparatus 50 may comprises a different number of output channels 88 .
  • Pumps 90 may comprise any suitable type of pump, such as a roller pump, for example, and may be used in any suitable pumping arrangement. One or more pumps 90 may be employed depending on the circulation paths that are most suitable for the density of microspheres 85 being fabricated.
  • Microsieves 94 may be designed to capture microspheres 85 while allowing underlying medium 82 to pass therethrough. Microspheres 85 captured in microsieves 94 may then be extracted (e.g., manually or by any other suitable means) for washing and further processing.
  • method 200 then proceeds to block 212 , which involves washing off any residual macropore spacers 68 and solvents from microspheres 85 , resulting in clean microspheres 20 comprising only base polymer 22 with bimodal pore distributions.
  • the block 212 washing process may not be necessary if microspheres 85 are sufficient cleaned as they circulate through medium 82 in tower 80 (depending on the choice of medium 82 ).
  • the block 212 washing process for removing macropore spacers 68 may involve leaching (i.e. dissolution of macropore spacers 68 in a suitable liquid or gas solvent), application of heat and/or sublimation or other suitable techniques for removal of residual macropore spacers 68 and solvents.
  • macropore spacers 68 are salt crystals or other water-soluble materials
  • the washing process may involve leaching microspheres 85 in water.
  • microspheres 85 may be placed in a vessel connected to a vacuum pump for a time needed for complete sublimation of the solvents.
  • the block 212 washing process need not remove macropore spacers 68 .
  • macropore spacers 68 may comprise bioactive substances that may initially remain incorporated into the macropore of microspheres 20 as opposed to being washed out and which may subsequently be taken up by the organism into which microspheres 20 are deployed. At the conclusion of block 212 , microspheres 20 are ready for further processing and/or application as described further below.
  • method 200 may comprise an additional step (not explicitly shown) of sterilizing microspheres 20 .
  • sterilization may involve using suitable external radiation or gas-based sterilization processes.
  • method 200 may also involve sorting microspheres 20 by size (not explicitly shown) so that microspheres 20 within a particular size range may be selected for particular applications. Such sorting may be accomplished, for example, using an arrangement of microsieves of varying fineness.
  • base polymer 22 comprises a biocompatible polymer or monomer, which can also be bioabsorbable and/or biodegradable.
  • the base polymer is sufficiently mechanically rigid at room temperatures and body temperatures, such that the microspheres maintain their shape and pore structure during the washing phase of the fabrication process and during subsequent processing and application in vivo.
  • Non-limiting examples of bioabsorbable polymers that are suitable for use as a base polymer (or at least a part of a base polymer) include one or more of:
  • bioabsorbable materials that could be used to provide a base polymer (or at least a part of a base polymer) include absorbable biocompatible biomass products such as one or more of:
  • a base polymers as used herein include one or more of: polyethylene oxide/polyethylene terephthalate and copolymers thereof; copolymers of lactic or glycolic acid or combinations of the two with hydroxy-ended flexible chains, such as poly(alkylene glycols) of various molecular weights and forms and commercially available.
  • poly(alkylene glycols) include, but are not limited to, hydroxyl-terminated polyethylene oxide, polypropylene oxide, poly(oxyethylene-co-oxypropylene) and polytetramethylene oxide chains, poly(oxyethylene glycols), poly(oxypropylene)-poly(oxyethylene)-glycols block copolymers and poly(oxybutylene)glycols.
  • a base polymer as used herein include one or more of: biodegradable and biocompatible polycaprolactones, polyhydroxybutyrates and copolymers of polyesters, polycarbonates, polyanhydrides and poly(ortho esters); bisphenol-A based polyphosphoesters such as poly(bisphenol-A phenylphosphate), poly(bisphenol-A ethylphosphate), poly(bisphenol-A ethylphosphonate), poly(bisphenol-A phenylphosphonate), poly[bis(2-ethoxy)hydrophosphonic terephthalate], and copolymers of bisphenol-A based poly(phosphoesters); polymers derived from tyrosine-derived diphenol monomers having an exemplary structure as follows:
  • R 1 is —CH ⁇ CH— or (—CH 2 —) n , in which n is zero or an integer from one to eight; and R 2 is selected from straight and branched alkyl and alkylaryl groups containing up to 18 carbon atoms.
  • the diphenol compounds can be polymerized to form, for example, polyiminocarbonates, polycarbonates, polyacrylates, polyurethanes or polyethers. See, e.g., U.S. Pat. Nos. 5,099,060 and 5,198,507 for methods of preparing polyiminocarbonates and polycarbonates.
  • Suitable diphenol monomers for use in the methods provided herein include, by way of illustration, desaminotyrosyl-tyrosine (DT) esters such as desaminotyrosyl tyrosine ethyl ester (DTE), desaminotyrosyl tyrosine butyl ester (DTB), desaminotyrosyl tyrosine hexyl ester (DTH), desaminotyrosyl tyrosine octyl ester (DTO), or a combination thereof.
  • DTE desaminotyrosyl tyrosine ethyl ester
  • DTB desaminotyrosyl tyrosine butyl ester
  • DTH desaminotyrosyl tyrosine hexyl ester
  • DTO desaminotyrosyl tyrosine octyl ester
  • a base polymer includes one or more of: polycarbonates, polyimino-carbonates, polyarylates, polyurethanes, strictly alternating poly(alkylene oxide ethers), poly(alkylene oxide) block copolymers polymerized from dihydroxy monomers prepared from ⁇ - and ⁇ -hydroxy acids and derivatives of tyrosine, block copolymers of polycarbonates and polyarylates with poly(alkylene oxides), polycarbonates, polyimino carbonates, polyarylates, poly(alkylene oxide) block copolymers.
  • block copolymers of polycarbonates with poly(alkylene oxides) block copolymers of polyarylates with poly(alkylene oxides), ⁇ -hydroxycarboxylic acids, poly(capro-lactones), poly(hydroxybutyrates), polyanhydrides, poly(ortho esters) and polyesters bisphenol-A based poly(phosphoesters), or a combination thereof.
  • the particle comprises polyvinyl alcohol.
  • the particle comprises an acrylic, acrylamide or acrylate polymer or copolymer.
  • the particle comprises a polyvinyl alcohol and an acrylic, acrylamide or acrylate polymer or copolymer.
  • the particle comprises a trisacrylamide polymer.
  • the particle the base polymer is N-tris-hydroxymethyl methylacrylamide, diethylaminoathylacrylamide, N,N-methylene-bis-acrylamide, or a combination thereof.
  • the particle comprises a sodium acrylate and vinyl alcohol copolymer.
  • the particle further comprises a cell adhesion promoter, such as a gelatin.
  • the particle is crosslinked. In other embodiments, the particle is not crosslinked.
  • the above-described materials are non-limiting examples of possible materials for use as (or as part of) a base polymer. Still other non-limiting examples of such materials include iodine impregnated polymers or polymers containing free carboxylic acid pendent chains. It may also be possible to use apatite derivatives, such as hydroxyapatite and flourapatite, for a base polymer. Any of the above-described materials, or materials provided elsewhere herein, may be used alone or in any combination, for example as a monomer, polymer or copolymer thereof.
  • the first solvent may be characterized by being a solvent in which a base polymer 22 is soluble in varying concentrations.
  • the first solvent is also miscible in the second solvent to form a continuous phase medium.
  • the first solvent may have a melting point between about ⁇ 20° C. and about +20° C., such that, at a high rate of cooling, crystallization is the favored phase separation mechanism (though the first solvent is not limited to this temperature range) and, in other particular embodiments, solvents may have melting points between about ⁇ 40° C. and about +40° C.
  • a compatible first solvent for a polylactic acid (PLA) derived base polymer is 1,4-dioxane, which has a melting point of 12° C. and a low crystallization energy.
  • Other solvents may be used for other base polymer materials.
  • the second solvent may be characterized by being a solvent in which a base polymer is immiscible or only miscible in very low concentrations.
  • the second solvent is, however, completely miscible in the first solvent.
  • a specific example of a second solvent compatible with a PLA base polymer and a 1,4-dioxane first solvent is water.
  • Other non-limiting examples of solvents that are suitable for use as the second solvent include alcohols such as, but not limited to, methanol, ethanol, isopropanol, tert-butanol and 1,3-propanediol.
  • a second solvent may also serve as a continuous phase in an emulsion consisting of a first solvent, a macropore spacer and an optional additive.
  • Macropore spacer material 68 may be characterized, in some embodiments, by being immiscible or only slightly miscible in the first solvent and base polymer 22 .
  • the macropore spacer material is miscible in the second solvent.
  • the macropore spacer material is largely miscible in the second solvent.
  • sodium chloride (table salt) provides a suitable macropore spacer material in the case where the second solvent is water. Salt has the additional benefit of being biocompatible should any residual quantities remain in microspheres 20 after washing (block 212 ).
  • macropore spacer material 68 may not be miscible in either the first or second solvents.
  • macropore spacer material 68 may be soluble in a third solvent used in the washing process 212 described above. In some embodiments, macropore spacer material 68 may be miscible in medium 82 of tower 80 , such that it is washed out during circulation through tower 80 . In some embodiments, macropore spacer material 68 may intentionally not be washed out such that it remains (at least initially) an additive incorporated into microsphere 20 for later application (for example, cisplatin may be used as macropore spacer material 68 where medium 82 is nitrogen based). Macropore spacer 68 may also be non-absorbable, dislodging from microsphere 20 as a result of bioerosion and resulting in embolization of smaller luminal structures (such as blood vessels).
  • control of the size of macropores 24 may depend on the overall size of crystals or particles used to provide macropore spacers 68 , as well as the timing of the introduction of macropore spacers 68 into solution 54 .
  • suitable macropore spacer materials 68 may include: biologically acceptable alkali metal and alkaline earth metal halides, phosphates, sulfates, and the like; crystals of sugars; microspheres of water-soluble polymers; and proteins, such as albumin.
  • the macropore spacer material 68 as used herein is sodium chloride.
  • Macropore spacer material 68 may also include smaller microspheres 20 or nanoparticles (which may or may not be bioabsorbable. Particles of these materials should be selected having the diameter that is desired for macropores 24 .
  • the macropore spacer material is an additive. In some embodiments, the macropore spacer material is cisplatin. In one embodiment, the macropore spacer material is cisplatin and the medium is a nitrogen-based medium. In certain embodiments, the macropore spacer material is bioabsorbable. In other embodiments, the macropore spacer material is not bioabsorbable. In certain embodiments, the macropore spacer material embolizes luminal structures, such as blood vessels. In certain embodiments, wherein the macropore spacer material is non-toxic and/or biocompatible.
  • the macropore spacer material is selected from the group consisting of an alkali metal and alkaline earth metal halides, phosphates, sulfates; sugars, crystals of sugars; water soluble polymers, microspheres, nanoparticles, microspheres of water-soluble polymers; proteins, albumin, and sodium chloride.
  • methods of fabricating microspheres 20 do not comprise one or more additives (e.g., bio-active material) into microspheres 20 .
  • methods of fabricating microspheres 20 may further comprise incorporating one or more additives (e.g., bio-active material) into microspheres 20 . This step may be performed at various stages of the fabrication process.
  • an additive could be introduced to polymer solution 54 before its injection into tower 80 , added to the pores of microspheres 20 after washing (block 212 ) and/or incorporated into macropore spacers 68 which initially remain present in microspheres 20 , or additives may act as initiators to the polymerization process.
  • an additive capable of withstanding the temperature fluctuations in the fabrication process is incorporated into polymer solution 54 before injection into tower 80 .
  • the additive can be provided to the solution within about 1, 5, 10, 15, 20, 30, 45 minutes or about 1, 2, 4, 6 hours of injection.
  • base polymer 22 and the first and second solvents may be pre-blended before the additive is dissolved therein or the additive may be dissolved in the solvent in which it is most soluble, after which the first and second solvents and base polymer 22 may be combined.
  • Such additive materials can become embedded in base polymer 22 when droplets 84 are quenched in tower 80 .
  • such additives may adhere to the surface of microspheres 20 by a variety of means such as through cross linking with base polymer 22 , ionic bonding, acid base reactions, receptor site attraction or gravitational forces.
  • the additive is provided to the solution after injection.
  • the additive is provided to the solution within about 1, 5, 10, 15, 20, 30, 45 minutes or about 1, 2, 4, 6 hours after injection.
  • the additive is provided to the solution during injection.
  • the additive is provided to the solution prior to quenching. In such embodiments, the additive can be provided to the solution within about 1, 5, 10, 15, 20, 30, 45 minutes or about 1, 2, 4, 6 hours of quenching. In other embodiments, the additive is provided to the solution after quenching. In such embodiments, the additive is provided to the solution within about 1, 5, 10, 15, 20, 30, 45 minutes or about 1, 2, 4, 6 hours after quenching. In some embodiments, the additive is provided to the solution during quenching.
  • the additive is provided to the solution prior to washing. In such embodiments, the additive can be provided to the solution within about 1, 5, 10, 15, 20, 30, 45 minutes or about 1, 2, 4, 6 hours of washing. In other embodiments, the additive is provided to the solution after washing. In such embodiments, the additive is provided to the solution within about 1, 5, 10, 15, 20, 30, 45 minutes or about 1, 2, 4, 6 hours after washing. In some embodiments, the additive is provided to the solution during washing.
  • additives may be incorporated into or coated on microspheres 20 after the conclusion of method 200 .
  • the additive can be covalently attached to the polymer.
  • the additive is covalently attached to polymers having pendent free carboxylic acid groups using methods known in the art. See, for example, U.S. Pat. Nos. 5,219,564 and 5,660,822; Nathan et al., Bio. Congo Chem., 4, 54-62 (1992) and Nathan, Macromolecules, 25, 4476 (1992), which are incorporated herein by reference in their entirety.
  • hydrolytically stable conjugates are utilized when the additive is active in conjugated form.
  • Hydrolyzable conjugates are utilized when the additive is inactive in conjugated form.
  • the additive can be incorporated into or coated onto the particle.
  • microspheres 20 can be coated with an anticoagulant (such as heparin) such that the anticoagulant becomes covalently attached to the surface of microsphere 20 through processes known in the art.
  • an anticoagulant such as heparin
  • microspheres 20 may be coated with bioactive substances that function as receptors or chemoattractors for a desired population of cells. Such coatings may be applied through absorption or chemical bonding.
  • the additive adheres to a surface of the particle.
  • the additive adheres to the surface of the microsphere by cross-linking with the base polymer, ionic bonding, acid base reactions, receptor site attraction or gravitational forces.
  • additives may be subsequently released from microsphere 20 in a controlled fashion in a selected target area of a living subject or may be activated by contact with surrounding fluids and tissues without being released from microsphere 20 .
  • Additives may be released by a bioerosion of microspheres 20 (if base polymer 22 is biodegradable), by diffusion from microspheres 20 , or by migration to the polymer surface of microspheres 20 .
  • the additive may be provided in a physiologically or pharmaceutical acceptable carrier, excipient, stabilizer, etc., and may be provided in sustained release or timed release formulations.
  • the additives may also incorporate agents to facilitate their delivery, such as antibodies, antibody fragments, growth factors, hormones, or other targeting moieties, to which the additives are coupled.
  • Additives suitable for use with microspheres 20 include biologically or pharmaceutically active compounds.
  • biologically active compounds include, but are not limited to, cell attachment mediators, such as the peptide containing variations of the “RGD” integrin binding sequence known to affect cellular attachment, biologically active ligands, and substances that enhance or exclude particular varieties of cellular or tissue ingrowth.
  • Such substances include, for example, osteoinductive substances, such as bone morphogenic proteins (BMP), epidermal growth factor (EGF), fibroblast growth factor (FGF), platelet-derived growth factor (PDGF), insulin-like growth factor (IGF-I and II), TGF- ⁇ , vascular endothelial growth factor (VEGF), tumor necrosis factor (TNF), tumor induction factor (TIF), and the like.
  • BMP bone morphogenic proteins
  • EGF epidermal growth factor
  • FGF fibroblast growth factor
  • PDGF platelet-derived growth factor
  • IGF-I and II insulin-like growth factor
  • TGF- ⁇ vascular endothelial growth factor
  • VEGF vascular endothelial growth factor
  • TNF tumor necrosis factor
  • TNF tumor induction factor
  • Examples of pharmaceutically active compounds include, but are not limited to, acyclovir, cephradine, malfalen, procaine, ephedrine, adriomycin, daunomycin, plumbagin, atropine, guanine, digoxin, quinidine, biologically active peptides, chlorin e 6, cephalothin, proline and proline analogues such as cis-hydroxy-L-proline, penicillin V, aspirin, ibuprofen, steroids, nicotinic acid, chemodeoxycholic acid, chlorambucil, and the like.
  • bioactive substances that may be used as additives include vasodilators such as nitrates (nitroglycerin, nitrous oxide based materials), calcium channel blockers (commercial name verapamil), thromobolyics (such as tissue plasminogen factor (TPA), Streptokinase, Urokinase), antiplatelet aggregation/adhesion factors (such as IIa-IIIb inhibitors, commercial name reopro).
  • vasodilators such as nitrates (nitroglycerin, nitrous oxide based materials), calcium channel blockers (commercial name verapamil), thromobolyics (such as tissue plasminogen factor (TPA), Streptokinase, Urokinase), antiplatelet aggregation/adhesion factors (such as IIa-IIIb inhibitors, commercial name reopro).
  • vasodilators such as nitrates (nitroglycerin, nitrous oxide
  • Non-limiting examples of conventional chemotherapeutics include platinum class chemotherapeutics, topoisomers, topo inhibitors and reverse transcriptase chemotherapeutics.
  • Non-limiting examples of biological chemotherapeutics include bevacizumab, cetuximab, 3-bromopyruvate, small molecule biologics such as sorafenib and multikinase inhibitors.
  • Other exemplary additives are the therapeutic agents and drugs provided elsewhere herein.
  • the additive as used in conjunction with the bimodal particles or microspheres, compositions and methods provided herein is one or more therapeutic agents.
  • Therapeutic agents that can be used in combination with the microspheres in the compositions, methods or kits provided herein include (e.g., one, two, three, four or more) agent(s), such as a drug.
  • agent(s) such as a drug.
  • a therapeutic agent can be any one or more of an anti-neoplastic drug, anti-angiogenesis drug, anti-fungal drug, anti-viral drug, anti-inflammatory drug, anti-bacterial drug, a cytotoxic drug, a chemotherapeutic or pain relieving drug and/or an anti-histamine drug.
  • the therapeutic agent can also be, for example, any one or more of hormones, steroids, vitamins, cytokines, chemokines, growth factors, interleukins, enzymes, anti-allergenic agents, circulatory drugs, anti-tubercular agents, anti-anginal agents, anti-protozoan agents, anti-rheumatic agents, narcotics, cardiac glycoside agents, sedatives, local anesthetic agents, general anesthetic agents, and combinations thereof.
  • Such therapeutic agents can also include, for example, antineoplastic, angiogenic factors, immuno-suppressants, or antiproliferatives (anti-restenosis agents).
  • therapeutic agents include embryonic factors, fibroblast growth factors, transcription factors, kinase inhibitors, or adenosine.
  • the therapeutic agent is an anti-neoplastic, chemotherapeutic or pain relieving drug.
  • anti-angiogenic or anti-neoplastic drugs include, but are not limited to, AGM-1470 (TNP-470), angiostatic steroids, angiostatin, antibodies against av ⁇ 3, antibodies against bFGF, antibodies against IL-1, antibodies against TNF- ⁇ , antibodies against VEGF, auranofin, azathioprine, BB-94 and BB-2516, basic FGF-soluble receptor, carboxyamido-trizole (CAI), cartilage-derived inhibitor (CDI), chitin, chloroquine, CM 101, cortisone/heparin, cortisone/hyaluroflan, cortexolone/heparin, CT-2584, cyclophosphamide, cyclosporin A, dexamethasone, diclofenac/hyaluronan, eosinophilic major basic protein, fibronectin peptides, Glioma-derived angiogenesis inhibitory factor (GD-AIF), GM 1474
  • the anti-angiogenic agent is selected from the group consisting of thalidomide, 3-aminothalidomide, 3-hydroxythalidomide and metabolites or hydrolysis products of thalidomide, 3-aminothalidomide, 3-hydroxythalidomide.
  • the anti-angiogenic agent is thalidomide.
  • anti-angiogenic or anti-neoplastic drugs include, without limitation, alkylating agents, nitrogen mustards, antimetabolites, gonadotropin releasing hormone antagonists, androgens, antiandrogens, antiestrogens, estrogens, and combinations thereof.
  • Specific examples include but are not limited to actinomycin D, aldesleukin, alemtuzumab, alitretinoin, allopurinol, altretamine, amifostine, aminoglutehimide, amphotercin B, amsacrine, anastrozole, ansamitocin, arabinosyl adenine, arsenic trioxide, asparaginase, aspariginase Erwinia , BCG Live, benzamide, bevacizumab, bexarotene, bleomycin, 3-bromopyruvate, busulfan, calusterone, capecitabine, carboplatin, carzelesin, carmustine, celecoxib, chlorambucil, cisplatin, cladribine, cyclophosphamide, cytarabine, cytosine arabinoside, dacarbazine, dactinomycin, darbepoetin alf
  • the platinum compound is spiroplatin, cisplatin, or carboplatin.
  • the drug is cisplatin, mitomycin, paclitaxel, tamoxifen, doxorubicin, tamoxifen, or mixtures thereof.
  • pain reliving drugs are, without limitation, analgesics or anti-inflammatories, such as non-steriodal anti-inflammatory drugs (NSAID), ibuprofen, ketoprofen, dexketoprofen, phenyltoloxamine, chlorpheniramine, furbiprofen, vioxx, celebrex, bexxstar, nabumetone, aspirin, codeine, codeine phosphate, acetaminophen, paracetamol, xylocalne, and naproxin.
  • the pain relieving drug is an opioid.
  • Opioids are commonly prescribed because of their effective analgesic, or pain relieving, properties.
  • narcotics such as morphine, codeine, and related medications.
  • opioids include oxycodone, propoxyphene, hydrocodone, hydromorphone, and meperidine.
  • Narcotics include, for example, without limitation, paregoric and opiates, such as codeine, heroin, methadone, morphine and opium.
  • Hormones and steroids include, for example, without limitation, growth hormone, melanocyte stimulating hormone, adrenocortiotropic hormone, dexamethasone, dexamethasone acetate, dexamethasone sodium phosphate, cortisone, cortisone acetate, hydrocortisone, hydrocortisone acetate, hydrocortisone cypionate, hydrocortisone sodium phosphate, hydrocortisone sodium succinate, prednisone, prednisolone, prednisolone acetate, prednisolone sodium phosphate, prednisolone tebutate, prednisolone pivalate, triamcinolone, triamcinolone acetonide, triamcinolonehexacetonide, triamcinolone acetate, methylprednisolone, methylprednisolone acetate, methylprednisolone sodium succinate, flunsolide, be
  • Peptides and peptide analogs include, for example, without limitation, manganese super oxide dismutase, tissue plasminogen activator (t-PA), glutathione, insulin, dopamine, peptide ligands containing RGD, AGD, RGE, KGD, KGE or KQAGDV (peptides with affinity for theGPEXma receptor), opiate peptides, enkephalins, endorphins and their analogs, human chorionicgonadotropin (HCG), corticotropin release factor (CRF), cholecystokinins and their analogs, bradykinins and their analogs and promoters and inhibitors, elastins, vasopressins, pepsins, glucagon, substance P, integrins, captopril, enalapril, lisinopril and other ACE inhibitors, adrenocorticotropic hormone (ACTH), oxytocin, calc
  • Antibodies include, for example, without limitation, substantially purified antibodies or fragments thereof, including non-human antibodies or fragments thereof.
  • the substantially purified antibodies or fragments thereof can be human, non-human, chimeric and/or humanized antibodies.
  • Such non-human antibodies can be goat, mouse, sheep, horse, chicken, rabbit, or rat antibodies.
  • the antibodies can be monoclonal or polyclonal antibodies.
  • Anti-mitotic factors include, without limitation, estramustine and its phosphorylated derivative, estramustine-phosphate, doxorubicin, amphethinile, combretastatin A4, and colchicine.
  • Anti-coagulation agents include, for example, without limitation, phenprocoumon and heparin.
  • Anti-viral agents include, for example, without limitation, acyclovir, amantadine azidothymidine (AZT or Zidovudine), ribavirin, and vidarabine monohydrate (adenine arabinoside,ara-A).
  • Anti-anginal agents include, for example, without limitation, diltiazem, nifedipine, verapamil, erythritol tetranitrate, isosorbide dinitrate, nitroglycerin (glyceryl trinitrate), and pentaerythritolteiranitrate.
  • Antibiotics include, for example, dapsone, chloramphenicol, neomycin, cefaclor, cefadroxil, cephalexin, cephradine erythromycin, clindamycin, lincomycin, amoxicillin, ampicillin, bacampicillin, carbenicillin, dicloxacillin, cyclacillin, picloxacillin, hetacillin, methicillin, nafcillin, oxacillin, penicillin G, penicillin V, ticarcillin, rifampin, and tetracycline.
  • Anti-inflammatory agents and analgesics include, for example, diflunisal, ibuprofen, indomethacin, meclofenamate, mefenamic acid, naproxen, oxyphenbutazone, phenylbutazone, piroxicam, sulindac, tolmetin, aspirin and salicylates.
  • Circulatory drugs include, for example, without limitation, propranolol.
  • Cardiac glycoside agents include, for example, without limitation, deslanoside, digitoxin, digoxin, digitalin and digitalis.
  • Neuromuscular blocking agents include, for example, without limitation, atracurium mesylate, gallamine triethiodide, hexafluorenium bromide, metocurine iodide, pancuronium bromide, succinylcholine chloride(suxamethonium chloride), tubocurarine chloride, and vecuronium bromide.
  • Sedatives include, for example, without limitation, amobarbital, amobarbital sodium, aprobarbital, butabarbital sodium, chloral hydrate, ethchlorvynol, ethinamate, flurazepam hydrochloride, glutethimide, methotrimeprazine hydrochloride, methyprylon, midazolam hydrochloride paraldehyde, pentobarbital, pentobarbital sodium, phenobarbital sodium, secobarbital sodium, talbutal, temazepam, and triazolam.
  • Local anesthetic agents include, for example, without limitation, bupivacaine hydrochloride, chloroprocaine hydrochloride, etidocaine hydrochloride, lidocaine hydrochloride, mepivacaine hydrochloride, procaine hydrochloride, and tetracaine hydrochloride.
  • General anesthetic agents include, for example, without limitation, droperidol, etomidate, fentanyl citrate with droperidol, ketamine hydrochloride, methohexital sodium, and thiopental sodium.
  • Radioactive particles or ions include, for example, without limitation, strontium, rhenium, yttrium, technetium, and cobalt.
  • microspheres 20 may provide a delivery vehicle for various therapies or other additives to localized target areas in the body, allowing for extended, controlled exposure of the therapy or other additive to the target area.
  • Microspheres 20 may be doped, admixed, coated, or impregnated with a desired therapeutic agent or other additive and injected into to the targeted area by any suitable means.
  • microspheres 20 could potentially deliver any of the following additives: chemotherapy, immunomodulators, viral vectors, chemoattractants, polypeptides, neurotransmitters, biologics (e.g. bevacizumab), antibody receptor sites, antibodies, antibiotics and tissue differentiating signaling materials.
  • molecular antennae may be attached to the microsphere structure to provide sites for antibody binding, acid base reaction, ionic binding, additional crosslinking, and hydrophilic/phobic receptor sites.
  • additives are provided elsewhere herein.
  • an amount of additive is incorporated into porous microspheres 20 that will provide optimal efficacy to the subject, typically a mammal.
  • the subject is in need of the treatment thereof.
  • the dose and method of administration will vary from subject to subject and be dependent upon such factors as the type of mammal being treated, its sex, weight, diet, concurrent medication, overall clinical condition, the particular compounds employed, the specific use for which these compounds are employed and other factors which those skilled in the art will recognize.
  • an additive dosage ranges from about 0.001 mg/kg to about 1000 mg/kg, such as from about 0.01 mg/kg to about 100 mg/kg or from about 0.10 mg/kg to about 20 mg/kg.
  • the additives may be used alone or in combination with other therapeutic or diagnostic agents.
  • the drug is delivered to the patient (e.g., in a region of the patient) for the purposes, for example, of treating or managing a condition (i.e., a disease state, malady, disorder, etc.) in the patient.
  • a condition i.e., a disease state, malady, disorder, etc.
  • the drugs can be used as above or can be incorporated into other embodiments, such as emulsions.
  • compositions comprising any of the microspheres described above and a pharmaceutically acceptable liquid or other biocompatible carrier.
  • the compositions can be in the form of a suspension, a hydrogel, or an emulsion.
  • the composition can also be a suspension of said microspheres in said liquid.
  • the compositions are sterile.
  • the pharmaceutically acceptable liquid can be, without limitation, saline, a buffer-solution, water, an isotonic solution, a biological fluid or a mixture thereof.
  • the liquid can also be a salt solution, and, in certain embodiments, is composed of cations selected from the group consisting of sodium, potassium, calcium, magnesium, iron, zinc, and ammonium, for example, in an amount of from about 0.01 M to about 5 M.
  • the composition can comprise the microspheres in an amount from about 10% to about 90% by weight and the liquid (or other biocompatible carrier) in an amount from about 10% to about 90% by weight.
  • the composition can also comprise the microspheres in an amount from about 10% to about 50% by weight and the liquid (or other biocompatible carrier) in an amount from about 50% to about 90% by weight.
  • Acceptable pharmaceutical carriers for therapeutic use include diluents, solubilizers, lubricants, suspending agents, encapsulating materials, solvents, thickeners, dispersants, buffers such as phosphate, citrate, acetate and other organic acid salts, anti-oxidants such as ascorbic acid, preservatives, low molecular weight (less than about 10 residues) peptides such as polyarginine, proteins such as serum albumin, gelatin or immunoglobulins, hydrophilic polymers such as poly(vinylpyrrolindinone), amino acids such as glycine, glutamic acid, aspartic acid or arginine, monosaccharides, disaccharides, and other carbohydrates including cellulose or its derivatives, glucose, mannose or dextrines, chelating agents such as EDTA, sugar alcohols such as mannitol or sorbitol, counter-ions such as sodium and/or non-ionic surfactants such as tween, pluronics or P
  • the biocompatible carrier is an aqueous-based solution, a hydro-organic solution, an organic solution, a non-aqueous solution, or a mixture thereof.
  • the biocompatible carrier comprises a salt composed of cations, such as sodium, potassium, calcium, magnesium, iron, zinc, ammonium, and mixtures thereof, for example, in an amount of from about 0.01 M to about 5 M.
  • An additive e.g., a therapeutic agent loaded into or onto the microspheres can be released in vivo due to physiological processes. Release of the drug loaded onto the microspheres can be influenced by pH and salt concentrations. For example, drug release can be accelerated by establishing pH changes or changes in ionic strength in the environment surrounding the microspheres. Determination of such optimal drug-release conditions can easily be determined by those skilled in the art.
  • an additive e.g., a therapeutic agent
  • the additive is released over a certain number of hours, days, or weeks.
  • about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, or about 100% of the drug has been released from the microsphere after a certain period of time, for example, after about 3 hours, about 6 hours, about 12 hours, about 18 hours, or after about 1 day, about 2 days, about 3 days, about 4 days, about 5 days, about 6 days, or after about 1 week, about 2 weeks, about 3 weeks, about 4 weeks, about 5 weeks, about 6 weeks, about 7 weeks, about 8 weeks, about 9 weeks, or about 10 weeks or longer.
  • Drug release properties will depend, in part, on the properties of the specific drug used, but will be readily determinable by those
  • an additive e.g., at therapeutic agent
  • Biocompatible bimodal porous microspheres 20 may have a wide variety of medical applications.
  • the microspheres provided herein can be used for tissue engineering, tissue guided regeneration, in vivo stem cell harvesting, culturing, or differentiation, delivery and suspension of therapeutic materials in targeted human or animal tissues and/or other applications.
  • the size of microspheres 20 allow them to be delivered with relative ease to virtually any target region of a living subject (e.g. by non-surgical means, such as by catheter, needle, tubing or the like) and the porous structure of microspheres 20 allow them to be of versatile application within these target regions, for example in delivering prolonged localized therapy or in promoting cell growth and transplantation.
  • microspheres in the compositions and methods provided herein can be administered to (or otherwise contacted with) a tissue or organ (e.g., heart, kidney, spinal cord, uterus, liver or pancreas) by methods known in the art.
  • the microspheres are administered (e.g., by injection) to a tissue or organ that has more than one blood supply, for example the liver, lung, spine, spinal cord, uterus or pancreas.
  • the particle is administered to the heart, lung, nervous system, brain, lung, liver, uterus or pancreas of the patient.
  • the particle is administered to one or more blood vessels, veins or arteries comprised within the tissue or organ.
  • the bimodal porous microspheres provided herein are used to counter ischemia in the target area, e.g., the area of administration or injection, such as in or near a tissue or organ.
  • the microspheres are administered to a patient by intraluminal administration or injection. In other embodiments of the methods provided herein, the microspheres are administered to a patient by intravascular administration or injection.
  • the microspheres can be delivered systemically or locally to the desired tissue or organ.
  • the microspheres can be administered to a tissue or organ before, during or after a surgery.
  • the microspheres are delivered to a tissue or organ using non-surgical methods, for example, either locally by direct injection into the selected tissues, to a remote site and allowed to passively circulate to the target site, or to a remote site and actively directed to the target site with a magnet.
  • non-surgical delivery methods include, for example, infusion or intravascular (e.g., intravenous or intraarterial), intramuscular, intraperitoneal, intrathecal, intradermal or subcutaneous administration.
  • the diseases or disorders above can be treated or otherwise managed by administering to the patient a therapeutically effective amount of the microspheres or a pharmaceutical composition provided herein.
  • Administration is typically carried out by injection.
  • the microspheres are administered by a catheter.
  • the microspheres are injected us a needle attached to a syringe.
  • administration is into a blood vessel.
  • administration is directly to the site of action, for example into a tumor mass, or into a cell, organ or tissue requiring such treatment or management.
  • the microspheres provided herein can be administered already loaded with a drug.
  • the microspheres are administered in combination with a drug solution, wherein the drug solution is administered prior, simultaneously or after the administration of the microspheres.
  • the microspheres or the pharmaceutical composition are suitable for injection.
  • the microspheres or compositions comprising the microspheres are sterile.
  • the microspheres may be sterilized by any method known in the art, for example, by irradiation, such as gamma or beta irradiation.
  • the microspheres are prepared aseptically using aseptic techniques.
  • the microspheres prepared aseptically comprise an additive, such as a therapeutic agent or drug.
  • compositions and methods suitable for treating or otherwise managing tumors or other cancers, non-tumorigenic angiogenesis-dependent diseases, or pain, such as pain related to the presence of a tumor or other cancer, or a symptom thereof include, without limitation (both anatomically and by primary neoplastic site), liver, ovarian, breast, kidney, lung, pancreatic, thyroid, prostate, uterine, skin cancer, head and neck tumors, breast tumors, brain, bone, soft tissues (such as sarcoma, lipoma, malignany fibrous histiocytoma), blood (such as lymphoma), Kaposi's sarcoma, and superficial forms of bladder cancer.
  • the method of treatment or management may be the result of localized (or systemic) drug delivery released from the drug-loaded microspheres, either alone or in combination with embolic effects of the microspheres.
  • drug-loaded microspheres provided herein are administered to a site-specific location other than a blood vessel (e.g., directly into a tumor mass), and no vessel embolization occurs.
  • non-tumorigenic angiogenesis-dependent diseases which are characterized by the abnormal growth of blood vessels can also be treated, either via down-regulation or up-regulation, or otherwise managed with the microspheres or pharmaceutical compositions provided herein.
  • nontumorigenic angiogenesis-dependent diseases include, without limitation, hypertrophic scars and keloids, proliferative diabetic retinopathy, rheumatoid arthritis, arteriovenous malformations, lymphangitic malformations, venous malformations, atherosclerotic plaques, delayed wound healing, hemophilic joints, nonunion fractures Klippel Trenaunay Syndrome, Parkes Weber Syndrome, Osler-Weber-Rendu Syndrone, Blue Rubber Bleb Syndrome, cutnaoues and subcutaneous nevi, hemangiomas, leiomyomata, adenomas, hamartomas, psoriasis, pyogenic granuloma, s
  • the microspheres and compositions provided herein can be used to deliver drugs to various cells, tissues or organs in need thereof.
  • the microspheres and compositions can be used to treat or otherwise manage tumors or cancers, inflammatory diseases or other diseases associated with inflammation, or symptoms thereof.
  • the microspheres and compositions provided herein can be used to treat or otherwise manage uterine fibroids.
  • a drug or therapeutic agent can be administered to a tissue, organ or cell prior to administration of microspheres. In certain embodiments, a drug or therapeutic agent is administered between about 1 minute and about 60 minutes prior to administration of microspheres. In some embodiments, a drug or therapeutic agent is administered to a tissue, organ or cell within 1, 5, 10, 15, 20, 30, 45 minutes or about 1, 2, 4, 6, 10, 12, 18, 20 or 24 hours of administration of microspheres. In yet other embodiments, a drug or therapeutic agent is administered concurrently with microspheres. In certain embodiments, microspheres are administered to a tissue, organ or cell prior to administration of the a drug or therapeutic agent. In certain embodiments, microspheres are administered between about 1 minute and about 60 minutes prior to administration of a drug or therapeutic agent. In some embodiments, microspheres are administered to a tissue, organ or cell within 1, 5, 10, 15, 20, 30, 45 minutes or about 1, 2, 4, 6, 10, 12, 18, 20 or 24 hours of administration of a drug or therapeutic agent.
  • microspheres may be administered simultaneously with cell delivery, which may include without limitation pancreatic islet cell transplantation for diabetes, stem cell administration for myocardial synthesis or preservation, bone promotion or synthesis within osseous structures, and catheter based stem cell administration to liver or lung.
  • cell delivery may include without limitation pancreatic islet cell transplantation for diabetes, stem cell administration for myocardial synthesis or preservation, bone promotion or synthesis within osseous structures, and catheter based stem cell administration to liver or lung.
  • cells can be administered to a tissue, organ prior to administration of microspheres.
  • cells e.g., stem cells
  • cells are administered between about 1 minute and about 60 minutes prior to administration of microspheres.
  • cells are administered to a tissue or organ within 1, 5, 10, 15, 20, 30, 45 minutes or about 1, 2, 4, 6, 10, 12, 18, 20 or 24 hours of administration of microspheres.
  • cells are administered concurrently with microspheres.
  • microspheres are administered to a tissue or organ prior to administration of the cells (e.g., stem cells).
  • microspheres are administered between about 1 minute and about 60 minutes prior to administration of cells. In some embodiments, microspheres are administered to a tissue or organ within 1, 5, 10, 15, 20, 30, 45 minutes or about 1, 2, 4, 6, 10, 12, 18, 20 or 24 hours of administration of cells (e.g., stem cells). In these various embodiments, cells and/or microspheres can be administered to a tissue or organ optionally with a drug or therapeutic agent.
  • an effective dose of cells for use in the methods provided herein will vary depending on the cell type used and/or the delivery site, and such doses can be readily determined by a physician.
  • the number of cells is in the range of 1 ⁇ 10 5 to 1 ⁇ 10 9 .
  • cells can be administered in a dose between about 1 ⁇ 10 6 and 1 ⁇ 10 8 , such as between 1 ⁇ 10 7 and 5 ⁇ 10 7 .
  • more or less cells can be used. For example, a larger region of damage may require a larger dose of cells, and a small region of damage may require a smaller does of cells.
  • an effective dose may be between 1 ⁇ 10 5 and 1 ⁇ 10 9 per kg of body weight, such as 1 ⁇ 10 5 , 1 ⁇ 10 6 , 1 ⁇ 10 7 , 1 ⁇ 10 8 , or 1 ⁇ 10 9 (or any range thereof) per kg of body weight, for example between 1 ⁇ 10 6 and 5 ⁇ 10 6 cells per kg of body weight.
  • Patient age, general condition, and immunological status may be used as factors in determining the dose administered, and will be readily determined by the physician.
  • compositions and methods provided herein which illustrate the potential functionality of microspheres 20 , are intraarterial brachytherapy, islet cell transplantation and others described below.
  • Intraarterial brachytherapy is a form of radiotherapy involving catheter-based infusion of radioactive materials through an artery to a target area within the body, typically for treatment or management of cancerous tissues or a symptom thereof.
  • the delivered radioactive materials may have an embolic effect (blocking off blood supply to the target area), which may be beneficial in maintaining the therapy in the target area.
  • embolic effect blocking off blood supply to the target area
  • such localized radiotherapy is typically dependent on generation of free radicals, and in particular oxygen free radicals. Generation of oxygen free radicals may be promoted by providing an oxygenated environment around the target area.
  • complete embolization in the target area may not be desirable since blood flow is required to provide oxygen.
  • a well oxygenated environment can result in increased radical generation, translating into a correspondingly increased radiotherapeutic effect.
  • porous microspheres 20 may provide a well suited material for intraarterial brachytherapy because they are capable of producing a local regional source of radioactivity (remaining in the target area) while allowing continued blood inflow (perfusion) to the target area and a minimal or optimal embolic effect. Furthermore, addition therapeutic agents may be incorporated into the microsphere structure for prolonged delivery to the target area.
  • Microspheres 20 may be made radioactive by various means, such as by coating them with a resin and/or subsequently bombarding microspheres 20 with radiation. Microspheres 20 may also be fabricated to incorporate radiopharmaceutical by covalent bonding to any of the materials used to form microspheres 20 (as described in U.S. patent application Ser. No. 10/762,507) or by the techniques described in U.S. Pat. No. 5,011,677.
  • Islet cell transplantation typically provides insulin-producing islet cells from a donor pancreas to a diabetic subject unable to produce insulin.
  • a load of islet cells are implanted into the portal vein of the recipient's liver through catheter-based infusion.
  • Current drawbacks to this technique are that the transplanted cells are injected as a suspension, which may result in cell to cell contact, increased compression of the cells, increased perfusion pressures, and local inflammatory reaction; all factors which contribute to apoptosis and transplant rejection.
  • Porous microspheres 20 may result in decreased cell density and may allow for continued perfusion, thereby increasing the probability of transplant survival.
  • the macropore structure within the microsphere may be designed to provide a scaffolding suitable for holding the islet cells a suitable distance apart, while the bimodal pore structure would permit suitable blood flow dynamics in and around the cells.
  • microspheres 20 may be used in stem cell therapy acting as an injectable scaffolding for supporting stem cell differentiation and tissue genesis.
  • injection of microspheres 20 may result in stem cell or targeted cell migration (for harvesting, processing, or differentiation into terminal cell lines) or in specific embodiments, in vitro creation of functional cell groups, or organs (organogenesis).
  • Particular non-limiting stem cell therapy applications include injection of microspheres 20 and stem cells into the liver or lungs which have unique anatomic characteristics—i.e. the liver has vascular inflow through both arterial supply and portal inflow and the lung has a dual inflow blood supply through the pulmonary artery and the bronchial arteries for concentration, harvesting or differentiation.
  • microspheres 20 may be coated or doped with various promoters, chemoattractants or cell potentiators that may promote cellular migration and/or differentiation and may facilitate establishment of local tissue regeneration in target areas.
  • Microspheres 20 comprising a base polymer that is bioabsorbable (or bioerodable or biodegradable) may have further advantages.
  • such microspheres 20 may decompose over time, leaving behind only the generated or transplanted cell structure.
  • Decomposable microspheres 20 may also allow for increased blood flow to delivered therapies and increased penetration of therapies into target tissues.
  • the gradual breakdown of microspheres 20 may also allow for the gradual delivery of localized therapy (such as drug therapy or radiation therapy) to the target area.
  • the method comprises administering a composition of bimodal porous microspheres, optionally in a biocompatible carrier, to a patient, such as a mammal.
  • tissue construction and generation methods provided herein provides the advantage of not being limited to the repair of any specific type of tissues or tissue defect in any specific organ or body part. Rather, the method is suitable for the construction and generation of defective tissues on any kind and of any parts of the body, including, but not limited to, heart, coronary vessels, blood vessels, spinal cord, bone, cartilage, tendon, ligament, breast, liver, gallbladder, bile duct, pancreas, intestinal tissues, urinary system, skin, hernia, and dental tissues.
  • compositions comprising a bimodal porous microsphere and a cell, such as a stem cell (e.g., a pluripotent mesenchymal stem cell) can improve tissue acceptance and the effectiveness of the treatment.
  • a stem cell e.g., a pluripotent mesenchymal stem cell
  • the methods provided herein can also increase connective tissue response.
  • tissue (or organ) construction or regeneration in a patient comprising administering cells, such as stem cells, to a patient.
  • the cells are contacted with the tissue or organ.
  • the patient is administered an injectable composition.
  • the injection can be carried out by conventional syringes and needles of 9 to 26 gauge.
  • the injection can also be facilitated by various techniques such as endoscopic delivery or laparoscopic technique.
  • the methods provided herein can offer additional and more beneficial therapeutic effects to further improve the tissue construction and generation.
  • the frequency and the amount of injection using the methods provided herein is determined based on the nature and location of the particular case of the tissue or organ defect being treated. In certain embodiments, multiple injections are not necessary. In other embodiments, however, repeated injection may be necessary to achieve optimal results. A skilled practitioner can determine the frequency and the amount of the injection for each particular case.
  • the microspheres after administration, become secured at the position of the injection and are not digested or eliminated by the lymphatic system, and/or the microspheres are not displaced from the position of injection.
  • the microspheres are bioabsorbable or biodegradable.
  • properties of certain bimodal porous microspheres provided herein allow the microspheres to provide a scaffold for effective tissue construction, tissue generation, and tissue engineering.
  • the ability of forming a scaffold at the injection site makes the microspheres provided herein particularly effective in providing tissue repair.
  • the size of the scaffold can be determined by the amount and frequency of the injection, which is in turn determined by the nature and location of the tissue construction and generation being performed. A skilled practitioner would be able to determine the exact amount and frequency of injection for each particular case.
  • microspheres provided herein can comprise cells, such as stem cells (e.g., mesenchymal stem cells) can promote new cell growth at the site of injection, makes the methods provided herein particularly effective in providing a mechanism for tissue construction and generation. Since, in certain embodiments, microspheres provided herein are bioabsorbable and/or biodegradable, they can be incorporated into the repaired tissue after serving as scaffold for the tissue generation.
  • stem cells e.g., mesenchymal stem cells
  • tissue construction and generation is accomplished by administering the microspheres comprising cells extra corporeally into organs, components of organs, or tissues prior to their inclusion into the body, organs, or components of organs.
  • the methods provided herein can be carried out by any type of sterile needles, e.g., from 9 to 26 gauge, and corresponding syringes or other means for injection, such as a three-way syringe.
  • the needles, syringes and other means for injection are commercially available from suppliers such as VWR Scientific Products (West Chester, Pa.), Beckton Dickinson, Kendal, and Baxter Healthcare.
  • the size of the syringe and the length of the needle used will dependent on the particular injection based on factors such as the specific disease or disorders being treated, the location and depth of the injection, and the volume and specific composition of the injectable suspension being used. A skilled practitioner will be able to make the selection of syringe and needle based on experience and the teachings provided herein.
  • a method of preparing an injectable suspension for use in the compositions and methods provided herein is as follows. Bimodal porous microspheres are washed, sterilized, and then mixed with cell culture containing cells, such as stem cells (e.g., mesenchymal stem cells). The cells are then detached from their original culturing surface, such as by trypsinization. The mixture of microspheres, cell culture medium and detached cells is allowed to continue a culturing process that is both sterile and suitable for stem cell culturing for a period of no less than 12 hours. The suspension is then ready for injection.
  • stem cells e.g., mesenchymal stem cells
  • the bimodal porous microspheres comprise cells, such as stem cells.
  • the cells are not human embryonic stem cells.
  • the cells are genetically engineered to express one or more polypeptides, such as a therapeutic agent, using techniques known in the art.
  • the cell comprises a nucleotide sequence that expresses the polypeptide, e.g., in a vector.
  • the cell expresses the polypeptide continuously.
  • the cell express the polypeptide transiently.
  • the cell can be regulated to express the polypeptide, e.g., by the use of an inducible promoter or other regulatory element in the vector comprising the nucleic acid sequence encoding the polypeptide.
  • the bimodal porous microspheres comprise genetic material.
  • Genetic material comprising nucleic acids, polynucleotides, RNA and DNA, of either natural or synthetic origin, including recombinant RNA and DNA and antisense RNA and DNA; hammerhead RNA, ribozymes, antigen nucleic acids, both single and double stranded RNA and DNA and analogs thereof, either in combination or not with other elements such as, for example, without limitation, tissue specific enhancers, and nuclear localization signals, can be introduced into eukaryotic cells via conventional transformation or transfection techniques.
  • transformation and “transfection” are intended to refer to a variety of art-recognized techniques for introducing foreign nucleic acid into a host cell, including, for example, without limitation, calcium phosphate or calcium chloride co-precipitation, DEAE-dextran-mediated transfection, lipofection, or electroporation. Suitable methods for transforming or transfecting host cells can be found in Sambrook et al. (2001) Molecular Cloning: A Laboratory Manual , Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., and other laboratory manuals.
  • a gene that encodes a selectable marker (e.g., for resistance to antibiotics) is generally introduced into the host cells along with the gene of interest.
  • selectable markers can include those which confer resistance to drugs, such as G418, hygromycin and methotrexate.
  • Cells stably transfected with the introduced nucleic acid can be identified by drug selection (e.g., cells that have incorporated the selectable marker gene will survive, while the other cells die).
  • transfection agents which are suitable for use with the methods provided herein include, without limitation, calcium phosphate or calcium chloride co-precipitation, DEAE-dextran-mediated transfection, quaternary ammonium amphiphile DOTMA ((dioleoyloxypropyl)trimethylammonium bromide, commercialized as Lipofectin by GEBCO-BRL))(Felgner et al, (1987) Proc. Natl. Acad. Sci. USA 84, 7413-7417; Malone et al. (1989) Proc. Natl. Acad. Sci.
  • DOTMA (dioleoyloxypropyl)trimethylammonium bromide, commercialized as Lipofectin by GEBCO-BRL)
  • DOTMA quaternary ammonium amphiphile
  • DOTMA (dioleoyloxypropyl)trimethylammonium bromide, commercialized as Lipofectin by GEBCO-BRL
  • metabolizable quaternary ammonium salts (DOTB, N-(1-[2,3-dioleoyloxy]propyl)-N,N,N-trimethylammonium methylsulfate (DOTAP)(Boehringer Mannheim), polyethyleneimine (PEI), dioleoyl esters, ChoTB, ChoSC, DOSC)(Leventis et al. (1990) Biochim. Inter.
  • CTAB cetyltrimethylammonium bromide
  • DOPE lipophilic diester of glutamic acid
  • CTAB didodecylammonium bromide
  • DDAB didodecylammonium bromide
  • stearylamine in admixture with phosphatidylethanolamine
  • Rose et al., (1991) Biotechnique 10, 520-525 DDAB/DOPE (TransfectACE, GIBCO BRL), and oligogalactose bearing lipids (Remy et al., to be published).
  • transfection enhancer agents can also be to increase the efficiency of transfer of the bioactive therapeutic factor into cells.
  • Suitable transfection enhancer agents include, for example, without limitation, DEAE-dextran, polybrene, lysosome-disruptive peptide (Ohmori N I et al., Biochem Biophys Res Commun Jun. 27, 1997; 235(3):726-9), chondroitan-based proteoglycans, sulfated proteoglycans, polyethylenimine, polylysine (Pollard H et al.
  • integrin-binding peptide CYGGRGDTP linear dextran nonasaccharide, glycerol, cholesteryl groups tethered at the 3′-terminal internucleoside link of an oligonucleotide (Letsinger, R. L. 1989 Proc Natl Acad Sci USA 86: (17):6553-6), lysophosphatide, lysophosphatidylcholine, lysophosphatidylethanolamine, and 1-oleoyl lysophosphatidylcholine.
  • suitable transfection agents include, without limitation, lipopolyamines as disclosed in U.S. Pat.
  • the microspheres provided herein comprise an expression vector.
  • the microspheres comprise a cell that comprises an expression vector.
  • the expression vector can contain a nucleic acid encoding a therapeutic agent or polypeptide (or a portion thereof).
  • the term “vector” refers to a nucleic acid molecule capable of transporting another nucleic acid to which it has been linked.
  • plasmid refers to a circular double stranded DNA loop into which additional DNA segments can be ligated.
  • Another type of vector is a viral vector, wherein additional DNA segments can be ligated into the viral genome.
  • viral vectors include, without limitation, adenovirus and retrovirus vectors for gene therapy using the microspheres and transfection agents provided herein.
  • a virus-like particle containing a bioactive therapeutic factor wherein the virus-like particle is physically linked to the transfection agent, which is also linked to the microparticle.
  • virus-like particles may be designed using polyethylenimine (PEI) conjugated to the integrin-binding peptide CYGGRGDTP via disuphide bridge formation.
  • PEI polyethylenimine
  • PEI/RGD-containing peptide/complexes share with adenovirus constitutive properties such as size and a centrally protected core, as well as early properties, such as cell entry mediated by integrins and acid-triggered endosome escape (Erbacher et al., to be published).
  • vectors are capable of autonomous replication in a host cell into which they are introduced (e.g., bacterial vectors having a bacterial origin of replication and episomal mammalian vectors). Other vectors (e.g., non-episomal mammalian vectors) are integrated into the genome of a host cell upon introduction into the host cell, and thereby are replicated along with the host genome. Moreover, certain vectors, expression vectors, are capable of directing the expression of genes to which they are operably linked. In general, expression vectors of utility in recombinant DNA techniques are often in the form of plasmids (vectors). However, other forms of expression vectors are also contemplated, such as viral vectors (e.g., replication defective retroviruses, adenoviruses and adeno-associated viruses), which serve equivalent functions.
  • viral vectors e.g., replication defective retroviruses, adenoviruses and adeno-associated viruses
  • the recombinant expression vectors used herein can comprise a nucleic acid in a form suitable for expression of the nucleic acid in a host cell.
  • the recombinant expression vectors include one or more regulatory sequences, selected on the basis of the host cells to be used for expression, which is operably linked to the nucleic acid sequence to be expressed.
  • “operably linked” is intended to-mean that the nucleotide sequence of interest is linked to-the regulatory sequence(s) in a manner which allows for expression of the nucleotide sequence (e.g., in an in vitro transcription/translation system or in a host cell when the vector is introduced into the host cell).
  • regulatory sequence is intended to include promoters, enhancers and other expression control elements (e.g. polyadenylation signals). Such regulatory sequences are described, for example, in Goeddel, Gene Expression Technology: Methods in Enzymology 185, Academic Press, San Diego, Calif. (1990). Regulatory sequences include those which direct constitutive expression of a nucleotide sequence in many types of host cell and those which direct expression of the nucleotide sequence only in certain host cells (e.g., tissue-specific regulatory sequences). It will be appreciated by those skilled in the art that the design of the expression vector can depend on such factors as the choice of the host cell to be transformed, the level of expression of protein desired, etc.
  • the expression vectors can be introduced into host cells to thereby produce proteins or peptides, including fusion proteins or peptides, encoded by nucleic acids as described herein.
  • the recombinant expression vectors can be designed for expression of a polypeptide in prokaryotic (e.g., E. coli ) or eukaryotic cells (e.g., insect cells (using baculovirus expression vectors), yeast cells, or mammalian cells). Suitable host cells are discussed further in Goeddel, Gene Expression Technology: Methods in Enzymology 185, Academic Press, San Diego, Calif. (1990).
  • the recombinant expression vector can be transcribed and translated in vitro, for example using T7 promoter regulatory sequences and T7 polymerase.
  • a nucleic acid is expressed in mammalian cells using a mammalian expression vector.
  • mammalian expression vectors include pCDM8 (Seed (1987) Nature 329:840) and pMT2PC (Kaufman et al. (1987) EMBO J. 6:187-195).
  • the expression vector's control functions are often provided by viral regulatory elements.
  • commonly used promoters are derived from polyoma, Adenovirus 2, cytomegalovirus and Simian Virus 40.
  • suitable expression systems for both prokaryotic and eukaryotic cells see Sambrook et al. (2001) Molecular Cloning: A Laboratory Manual , Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y.
  • the recombinant mammalian expression vector is capable of directing expression of the nucleic acid preferentially in a particular cell type (e.g., tissue-specific regulatory elements are used to express the nucleic acid).
  • tissue-specific regulatory elements are known in the art.
  • suitable tissue-specific promoters include the albumin promoter (liver-specific; Pinkert et al. (1987) Genes Dev. 1:268-277), lymphoid-specific promoters (Calame and Eaton (1988) Adv. Immunol. 43 235-275), in particular promoters of T cell receptors (Winoto and Baltimore (1989).
  • tissue-specific regulatory elements are known in the art.
  • suitable tissue-specific promoters include the albumin promoter (liver-specific; Pinkert et al. (1987) Genes Dev. 1:268-277), lymphoid-specific promoters (Calame and Eaton (1988) Adv. Immunol. 43 235-275), in particular promoters of T
  • mammary gland-specific promoters e.g., milk whey promoter, U.S. Pat. No. 4,873,316 and European Application Publication No. 264,166.
  • Developmentally-regulated promoters are also encompassed, for example the murine hox promoters (Kessel and Gruss (1990) Science 249:374-379) and the ⁇ .-fetoprotein promoter (Campes and Tilghman (1989) Genes Dev. 3:537-546).
  • the recombinant expression vector comprises a DNA molecule cloned into the expression vector in an antisense orientation. That is, the DNA molecule is operably linked to a regulatory sequence in a manner which allows for expression (by transcription of the DNA molecule) of an RNA molecule which is antisense to the mRNA encoding a given polypeptide.
  • Regulatory sequences operably linked to a nucleic acid cloned in the antisense orientation can be chosen which direct the continuous expression of the antisense RNA molecule in a variety of cell types, for instance viral promoters and/or enhancers, or regulatory sequences can be chosen which direct constitutive, tissue specific or cell type specific expression of antisense RNA.
  • the antisense expression vector can be in the form of a recombinant plasmid, phagemid or attenuated virus in which antisense nucleic acids are produced under the control of a high efficiency regulatory region, the activity of which can be determined by the cell type into which the vector is introduced.
  • a cancer may be treated by supplying a toxin gene on a DNA template with a tissue specific enhancer and/or promoter to focus expression of the gene in the cancer cells.
  • toxin genes include, without limitation, the diphtheria toxin gene. Intracellular expression of diphtheria toxin is known to kill cells.
  • tissue-specific promoters could be tissue-specific such as using a pancreas-specific promoter for pancreatic cancer.
  • a functional diphtheria toxin gene delivered to pancreatic cells could, in theory, eradicate the entire pancreas. This strategy could be used as a treatment for pancreatic cancer.
  • the tissue specific enhancer would ensure that expression of diphtheria toxin would only occur in pancreatic cells.
  • DNA/lipopolyamine/microsphere complexes containing the diphtheria toxin gene under the control of a tissue specific enhancer would be introduced directly into a cannulated artery feeding the pancreas. The infusion would occur on some dosing schedule for as long as necessary to eradicate the pancreatic tissue.
  • Other lethal genes besides diphtheria toxin could be used with similar effect, such as genes for ricin or cobra venom factor or enterotoxin.
  • prostate specific antigen promoter/enhancer to direct an additive, such as a therapeutic agent, to the prostate of a patient in need of treatment for prostatic cancer.
  • an additive such as a therapeutic agent
  • islet cells are modified by gene therapy.
  • methods of modifying islet cells through gene therapy approaches have been described to protect cells from apoptosis (see, e.g., Tellez et al. (2005) Gene Ther. 12:120-128; Giannoukakis et al. (1999) Diabetes 48:1730-1736), induce islet cell proliferation or augment directly the function of the transplanted tissue to promote disease treatment with fewer donor cells (see, e.g., Rao et al. (2004) Expert Opin. Biol. Ther. 4:507-5518; Lopez-Talayera et al. (2004) Endocrinol. 145:467-474)
  • porous microspheres 20 are described further below.
  • Microspheres 20 may be administered in vivo with active cell lines, or may act as a sieve to extract cells from the bloodstream for sequestration or differentiation due to the natural filtration of blood as it flows (perfuses) through microsphere 20 . Such perfusion through microsphere 20 may serve to decrease blood clot formation. Doping, coating or simultaneous administration of promoters, chemo attractants or cell potentiators may promote cellular migration and/or differentiation that could establish the bases for local tissue regeneration in solid organs, bone and cartilage, mucosa, endothelium, nervous, endocrine, or hematogenous tissues/cell lines for the purposes of tissue regeneration, differentiation, or altering the cellular constituent within a specific anatomical or histological environment.
  • Chemoembolization is a combination of chemotherapy and embolization or embolotherapy (as described above), used typically to treat cancer.
  • radioembolization is a combination of radiation therapy and embolization or embolotherapy.
  • Microspheres 20 may be injected to a target area as a standalone therapy or for the purposes of interspersion between terminal therapeutic embolics to allow for gradual migration of the embolic into tumor blood supply, while providing continued perfusion/blood flow into targeted tumor.
  • the addition of chemotherapeutics to the microsphere matrix may increase the efficacy of the therapy by improving the timing of exposure of therapy with the terminal embolic effect of embolic material.
  • Biogenerators are devices used for growing cells in vitro (external to a living body). Without being bound by any theory, the increased spacing that could be provided within a biogenerator through implementation of biocompatible (bioabsorbable or permanent) microspheres 20 could increase surface area for agitation, serve as binding sites and crypts for cellular ingrowth, and also decrease cell to cell contact which are all desirable criteria in biogenerator media.
  • Microspheres 20 comprising or containing iodine-impregnated polymers such as those described in PCT application PCT/US98/23777 may hold application for determination of true vascularity ratios of tumor or organ perfusion, as an alternative to Tc-99MAA, which has proven to be suboptimal due to its emulsified nature in applications of liver directed therapy.
  • Other non-limiting examples of tracers or imaging agents that may be added to microspheres 20 include radiolabelled antibodies, FDG, iondinated contrasts, ferromagnetic agents (such as small particle iron oxide (SPIO)), gadolinium chelates, magnesium, barium, or various diagnostic and/or therapeutic radioonucleoides.
  • SPIO small particle iron oxide
  • porous microspheres 20 may provide a vehicle for prolonged, controlled delivery of a large variety of topical and transdermal cosmetic substances such as fragrances, emollients, sunscreens, and anti-inflammatory, antifungal and antimicrobial agents, as described by Smith et al. in “The characteristics and utility of solid phase porous microspheres: a review”, Journal of Drugs in Dermatology, November-December, 2006. Incorporating such additives into microspheres 20 may decrease direct contact of the cosmetic additive with the surrounding tissue and thereby increase the metabolic half-life of the additive.
  • topical and transdermal cosmetic substances such as fragrances, emollients, sunscreens, and anti-inflammatory, antifungal and antimicrobial agents, as described by Smith et al. in “The characteristics and utility of solid phase porous microspheres: a review”, Journal of Drugs in Dermatology, November-December, 2006. Incorporating such additives into microspheres 20 may decrease direct contact of the cosmetic additive with the surrounding tissue and thereby increase the metabolic half-life of the
  • Localized intraluminal vascular and nonvascular
  • interstitial subdermal, transdermal, or subcutaneous injection and fixation of microspheres 20 may create a scaffolding for the administration of viscous materials for increased localized bioavailability and prolonged exposure.
  • Interporous distance may affect the degree of resorption and the local inflammatory reaction.
  • Simultaneous injection with hyaluronidase and the like may decrease resorption rate, and thus prolong efficacy of therapy.
  • microspheres 20 may allow for more efficient storage and maintenance of ex vivo cell lines than single slide methods which are currently in use.
  • Microspheres 20 may provide a suitable scaffolding or matrix within which the stored cells may be efficiently and safely packed.
  • a mixture of microspheres 20 and stem cells or non differentiated organ cell lines may be molded or formed into shapes that may serve as a basic functional unit for organ and tissue engineering.
  • microspheres 20 may also be applied in:
  • kits comprising one or more containers filled with one or more of the ingredients of the aforementioned microspheres and compositions provided herein.
  • the kits can comprise or more of microspheres, a contrast agent, and solution comprising one or more drugs, wherein one, two, three or more of the components can be in one, two, three or more vials.
  • Associated with such container(s) can be instructions for use and/or a notice in the form prescribed by a governmental agency regulating the manufacture, use or sale of pharmaceuticals or biological products, reflecting approval by the agency of the manufacture, use or sale of the product for patient (e.g., human or other mammal) administration.
  • the reagents of any of the assays or methods described herein can also be included as components of a kit.
  • the microspheres provided herein are present in a liquid, physiologically compatible solution in one vial.
  • the microspheres provided herein can be provided in dry form in one vial and the drug solution and contrast agent can be provided in a second and/or optionally a third vial.
  • the microsphere comprising the contrast agent are present in one vial, and the drug is present in solution in another vial.
  • the contents of the two vials can be mixed together prior to or concurrently with administration.
  • the microspheres comprising the contrast agent and the drug are provided in dry form in one vial. The powder can then be suspended in a suitable liquid prior to administration or a second vial is provided, which contains the injectable solution and the contents of both vials are combined prior to administration or concurrently with administration.
  • the microspheres provided herein are present in one vial and a second vial contains a pharmaceutically acceptable solution comprising the contrast agent.
  • the microspheres in the first vial can be pre-loaded with a drug, or the drug solution can optionally be present in a third vial.
  • the microspheres can then be mixed together with the drug solution and/or contrast agent, for example, prior to or concurrently with administration.
  • the microspheres are prepared by the following method using a bimodal porous microsphere fabricating apparatus. Briefly, 0.2 g of Poly(DTE carbonate) is stirred and dissolved in the mixture of 3 mL 1,4-dioxane and 0.3 mL water to form a homogenous solution in the storage vessel. The solution is subsequently poured into the chamber of the injector. 7 gram of sodium chloride is added to the solution via a conduit connected to the injector. A pressure is then applied to the injector chamber to allow injection of solution droplets into the quenching tower. The droplets are quickly frozen and solidified as soon as they enter into the tower, leaving bimodal porous structures. Next, residual salt and solvents are washed off from microspheres. The washing process is repeated several times until the silver nitrate test shows no additional release of chloride ions into the water. The resulting microspheres are removed from the water and dried to constant weight.
  • samples are prepared by cryofracture of the microspheres in liquid nitrogen.
  • the microspheres are submitted to a series of pressurization-depressurization to ensure the filling of the pores with water.
  • samples are dried under vacuum, mounted on metal stubs using adhesive tabs. They are coated with silver using a sputter coater.
  • An Hitachi S450 SEM at 15 kV is used for examination.
  • the sizes of the pores of the digital images obtained with the SEM are analyzed with the NIH Image 1.6 software. Evaluated image parameters include pore area, perimeter, major and minor axis of the ellipse. Adjustment of the digital images is made prior to pore assessment. The numbered pores are compared with the actual digital image to confirm pore location. Certain pore numbers which are not properly represented are excluded from the statistical data analysis. For each microsphere, at least 3 different digital images at 2 different magnifications (low magnification (scale bar of 200 ⁇ m) and high magnification (scale bar of 10 ⁇ m)), are analyzed.
  • Microspheres are analyzed as the macropore spacer material is still inside the polymer matrix.
  • the pore volume and the pore size distribution are determined by recording mercury intrusion volume into the microspheres at different pressures with a mercury porosimeter.
  • the filling pressure is recorded up to 3,000 psia. This pressure corresponds to the energy required to intrude mercury into pores of 0.06 ⁇ m or larger.
  • the pore diameter and porosity values refer to equivalent cylindrical pores with a diameter smaller than 310 ⁇ m.
  • D is the pore diameter in microns
  • P is the applied pressure (psia)
  • ⁇ is the surface tension between mercury and the scaffold surface (dynes/cm); and
  • ⁇ is the contact angle.
  • This solution is poured into paraffin oil at 50-70° C. stirring. After a few minutes, the polymerization reaction of acrylic monomers is manifested by an increase of temperature.
  • the macropore spacer material is then washed off or otherwise removed from the microspheres using the methods provided herein. The microspheres are then recovered by decanting, washed carefully, screened and sterilized in an autoclave in a buffered medium.
  • microspheres after screen calibration, possess the characteristics useful for embolization, including a marked cationic charge and an effective adhesion agent (gelatin or denatured collagen).
  • Particle size is managed by the speed of agitation of the emulsion. For example, in order to obtain microspheres with diameter around 300 ⁇ m (average dimension), the agitation speed is kept at about 250 rpm.
  • Hydrogel microspheres of polyvinylalcohol are then collected by filtration.
  • hydrogel microspheres of polyvinylalcohol may be collected by centrifugation or by simple decanting.
  • the macropore spacer material is then washed off or otherwise removed from the microspheres using the methods provided herein.
  • Residue oil is extracted by non-polar solvents or chlorinated solvents such as methylene chloride.
  • the resulting oil-free microspheres are then treated with a 0.5 M Tris-HCl buffer (pH 9) overnight at room temperature to neutralize excess aldehydes.
  • polyvinylalcohol microspheres are washed with physiological aqueous buffers, sieved to desired diameter, sterilized and stored as liquid suspensions. This material can be used for embolization procedure.
  • One-half of a gram of benzoyl peroxide as a polymerization initiator and 1-50 g of NaCl (or 1-50 g of insoluble microparticles having a diameter between 20 and 500 ⁇ m and molecular weight of 50-70 g/mol; or other suitable macropore space material) are added to 60 g of vinyl acetate and 40 g of methyl acrylate. This is dispersed in 300 ml of water containing 3 g of partially saponified polyvinylalcohol as a dispersion stabilizer and 10 g of NaCl. The suspension polymerization is carried at 65° C. for 6 hours. After removing the solvent, the polymer is dried for 24 hours in a freeze dryer.
  • the dried powder is suspended in a saponification fluid containing 200 g of methanol and 10 g of water. Then 40 ml of 10 N NaOH solution was added drop wise by maintaining the reaction at 10° C., and then the reaction was carried out at 30° C. for 24 hours. After the saponification reaction is completed, the reaction product is washed with methanol, after which 15.8 g of spherical dry saponified product with a particle diameter of about 50 ⁇ m to about 240 ⁇ m is obtained after drying. The macropore spacer material is also washed off or otherwise removed from the microspheres.
  • the product is then sieved and calibrated into, e.g., about 50 ⁇ m increments, to get several size ranges, e.g., about 50 ⁇ m-100 ⁇ m, about 100 ⁇ m-150 ⁇ m, about 150 ⁇ m-210 ⁇ m.
  • the sieved products can then be lyophilized.
  • An islet cell transplantation procedure is described as follows. Patients having C-peptide-negative type 1 diabetes for more than 5 years are included in the study on the basis of poor glycemic control, which is complicated by recurrent hypoglycemia or metabolic lability despite compliance with optimal medical therapy. Patients receive steroid-free immunosuppression therapy, which commences immediately prior to islet cell transplantation, with a regimen of five doses of daclizumab at a dose of mg/kg are administered i.v. over a period of 8 weeks after each transplantation. Strolimus is administered once daily to achieve a target therapeutic range of 12 to 15 ng/ml for three months after transplantation, after which the target trough range is lowered to 7 to 12 ng/ml. Tacrolimus is also administered twice daily and adjusted to achieve a target trough level of 3 to 6 ng/ml. In addition, patients are given a standard prophylactic antibiotics prior to commencement of the procedure.
  • Oxygen is administered via the nasal cannula at 6 L/min.
  • a right-sided percutaneous approach is used with patients positioned supine.
  • the point of hepatic puncture is determined by using fluoroscopy, ultrasonography, or a combination of both.
  • Total fluoroscopic time is recorded for each procedure.
  • the subcutaneous tissues and hepatic capsule are infiltrated with local anesthetic.
  • a 22-gauge Chiba needle is advanced into a branch of the right portal vein with fluoroscopic or US guidance.
  • a second- or third-order branch is selected in most cases.
  • An 18-gauge guidewire is then advanced into the main portal vein.
  • Islet cells are prepared essentially as described in Owen et al. (2003) Radial. 229:165-170. Briefly, pancreas organs are obtained from brain-dead donors after informed consent is received from relatives. The islet cells are isolated using a combination of enzymatic and mechanical dissolution and are prepared in xenoprotein-free medium. Islet cell transplantation proceeds if more than about 4000 purified islet cell equivalents are prepared and packed in cell volume of less than 10 ml, if ABO blood group compatibility matches, and if Gram stain was negative and endotoxin content is less than 5 endotoxin units/kg. The quantification of islet cells expressed in terms of islet cell equivalents accounts for variation in islet cell volume, with a standard islet cell measuring 150 ⁇ m.
  • the islet cells are administered to the patients following one of the treatment regimes:
  • Group I islet cells with bimodal porous microspheres.
  • Group II islet cells alone.
  • Group III microspheres alone.
  • Islet cell preparation is suspended in 120 mL of supplemented media (M199; Mediatech, Herndon, Va.) that contained heparin, 20% human albumin, and microspheres (in Group I). Heparin (35 U/kg) is added when the packed islet cell volume is less than 5 mL, and the amount of heparin is increased to 70 U/kg if the packed cell volume exceeded 5 mL.
  • the islet cells are administered either through this sheath or through a 5-F Kumpe catheter placed in the portal vein.
  • a specially designed stiffened micropuncture set can be used with a 4-F sheath designed to accept a 0.038-inch guidewire. The tract is embolized with gelatin sponge particles. Once the stiffened micropuncture kit is available, tract embolization is no longer performed routinely.
  • the islet cells with (Group I) or without (Group II) microspheres, or microspheres alone (Group III) are initially administered over approximately 10 minutes using a 60-mL syringe.
  • Portal venous pressure is recorded after the first 50-mL aliquot and after subsequent 50-mL aliquots.
  • a gravity-based closed infusion bag system can be used to minimize the shear forces on the islet cells to provide an alternative indirect method of continuous portal venous pressure monitoring and to reduce the risk of preparation contamination during islet cell delivery.
  • the procedure is terminated if portal venous pressure is higher than 20 mm Hg at the outset or if it increased to twice the baseline value or to higher than 22 mm Hg during the procedure.
  • the patients can undergo several time of infusions, depending on each individual's needs.
  • the catheter is removed with embolization of the tract by using gelatin sponge pledgets.
  • Complications are documented from data recorded at the time of the procedure, at clinical follow-up, and at confirmatory review of the radiology chart and images. Subjects will be evaluated for a reduction in the need for insulin, levels of fasting glucose and glycated hemoglobin, basal C-peptide secretion, and the mean amplitude of glycemic excursions over time.
  • the cell pellet is resuspended with 5 ml culture medium.
  • BMC bone marrow cells
  • RBC red blood cells
  • the gradient centrifugation method described by Yablonka-Reuveni and Nameroff is used ((1987) Histochem. 87:27-38).
  • the cell suspension is loaded on 20% to 60% gradient of Percoll, and the cells are centrifuges at 14,000 rpm for 10 min. The top two thirds of the total volume containing most of the BMC are transferred to a tube.
  • the cells are centrifuged at 2,000 rpm for 10 min. and then washed with PBS to remove the Percoll. This is repeated and the cell pellet is resuspended in culture medium and used for in vivo studies.
  • Mycardial Scar Generation Under general anesthesia, the rats were intubated and positive pressure ventilation (180 mL/min.) is maintained with room air supplemented with oxygen (2 L/min.) using a ventilator. The rat heart is exposed through a 2 cm left lateral thoracotomy. Cryoinjury is produced with a metal probe (8 ⁇ 10 mm in diameter) cooled to ⁇ 190° C. by immersion in liquid nitrogen and applied to the left ventrical free wall for 15 sec. This procedure was repeated 5 times and then applied for a total of 10 times with each lasting 1 min. The muscle layer and skin incision were closed with silk sutures. The rates are monitored for 4 hours postoperatively and penicillin is given by i.m. administration.
  • Group I BMC with bimodal porous microspheres.
  • Group III microspheres alone.
  • the rat heart is exposed through a midline sternotomy under general anesthesia.
  • Microspheres comprising varying concentrations of BMC (such as 10 6 ) cells (Group I), fifty microliters of BMC suspension containing 10 6 cells (Group II) or microspheres alone (Group III) are injected using a tuberculin syringe or other suitable catheter into the center of the left ventricular free wall scar tissue of each animal in the respective transplant groups.
  • the chest is closed with silk sutures, and antibiotics and analgesics are given.
  • Heart Function Measurements Five weeks after transplantation, the rats are anesthetized with ketamine and pentobarbital. A midline sternotomy is performed, the heart is removed and the animals are euthanized by exsanguinations. Heart function of the three groups is measured using a Langendorff apparatus and filtered Krebs-Henseleit buffer (in mmol/L: NaCl, 118; KCl, 4.7; KH 2 PO 4 , 1.2; CaCl 2 , 2.5; MgSO 4 1.2; NaHCO 3 , 25; and glucose, 11; pH 7.4) at the pressure of 100 mm Hg equilibrated with 5% CO 2 and 95% O 2 .
  • Krebs-Henseleit buffer in mmol/L: NaCl, 118; KCl, 4.7; KH 2 PO 4 , 1.2; CaCl 2 , 2.5; MgSO 4 1.2; NaHCO 3 , 25; and glucose, 11; pH 7.4
  • a latex balloon is passed into the left ventricle through the mitral valve and connected to a pressure transducer, a transducer amplifier, and differentiator amplifier.
  • the coronary flow of the heart is measures in triplicate by timed collection in the empty beating state without pacing.
  • the balloon size is increased by the addition of water in 20 ⁇ l increments from 40 ⁇ l until the left ventrical end-diastolic pressure reaches 30 mm Hg.
  • the systolic and diastolic pressures are recorded at each balloon volume and developed pressure is calculated.
  • the heart is weighed and its size is measured by water displacement.
  • Planimetry The scar size of left ventricular free wall is measured by the techniques of Pfeffer et al. (1991) Am. J. Physiol. 260:H1406-H1414 and Jugdutt and Khan. (1994) Circulation 89:2297-2307. Briefly, the hearts are fixed in distention (30 mm Hg) with 10% neutralized formalin and then cut into slices 3 mm thick. For each section, the outer and inner lines of the left ventricle are traced onto a transparency and quantified using computed planimetry (Jandal Scientific Sigma-Scan).
  • Tissue samples 0.5 cm 3 ) at the transplantation site are collected at 5 weeks after transplantation and fixed in neutralized 10% formaldehyde for histological study. The samples are embedded and cut to yield 10- ⁇ m thick sections, which are stained with hematoxylin and eosin as described in the manufacturer's specifications (Sigma Chemical Co).
  • Monoclonal antibodies against BrdU are used to localize the transplanted bone marrow cells. Briefly, samples are serially rehydrated with 100%, 95%, and 70% ethanol after deparaffinization with toluene. Endogenous peroxidase in the sample is blocked using 3% hydrogen peroxide for 10 minutes at room temperature. The sample is treated with pepsin for 5 minutes at 42° C. and 2N HCl for 30 minutes at room temperature. After rinsing with PBS 3 times, the sample is incubated with antibodies against BrdU in a moist chamber for 16 hours at room temperature. Negative control samples are incubated in PBS (without the primary antibodies) under the same conditions.
  • test and control samples are rinsed with PBS 3 times (15 minutes each) and then incubated with goat anti-rabbit immunoglobulin G conjugated with peroxidase at 37° C. for 45 minutes.
  • the samples are washed 3 times (15 minutes each) with PBS and then immersed in diaminobenzidine H 2 O 2 (2 mg/mL diaminobenzidine, 0.03% H 2 O 2 in 0.02 mL/L phosphate buffer) solution for 15 minutes. After washing with PBS, the samples are coverslipped and photographed.
  • the number of capillary vessels is counted in the scar tissue of all groups, using a light microscope at a ⁇ 400 magnification. Five high-power fields in each scar are randomly selected, and the number of capillaries in each is averaged and expressed as the number of capillary vessels per high-power field (0.2 mm 2 ).
  • Group I Subcutaneous injection of olive oil twice weekly at a dosage of 0.3 ml/kg body weight for the first 2 weeks and 0.2 ml/kg thereafter until the end of 12 weeks. Portal perfusion with normal saline administered at week 13 twice weekly for another 12 weeks.
  • Group II Subcutaneous injection of olive oil twice weekly at a dosage of 0.3 ml/kg body weight for the first 2 weeks and 0.2 ml/kg thereafter until the end of 12 weeks. Portal perfusion with bone marrow cells alone administered at week 13 twice weekly for another 12 weeks.
  • Group III Subcutaneous injection of olive oil twice weekly at a dosage of 0.3 ml/kg body weight for the first 2 weeks and 0.2 ml/kg thereafter until the end of 12 weeks. Portal perfusion with bone marrow cells plus bimodal porous microspheres administered at week 13 twice weekly for another 12 weeks.
  • Group IV Subcutaneous injection of 50% CCl 4 in olive oil twice weekly at a dosage of 0.3 ml/kg body weight for the first 2 weeks and 0.2 ml/kg body weight for another 12 weeks. Portal perfusion with normal saline administered at week 13 twice weekly for another 12 weeks.
  • Group V Administration of 50% CCl 4 as in Group IV. Portal perfusion with bone marrow cells alone Administered at week 13 twice weekly for another 12 weeks.
  • Group VI Administration of 50% CCl 4 as in Group IV. Portal perfusion with bone marrow cells plus bimodal porous microspheres administered at week 13 twice weekly for another 12 weeks.
  • All rabbits are subjected to surgery for permanent portal catheterization 2-9 days prior to portal perfusion. Under anesthesia, the rabbits are shaved of the hair coat with a razor and disinfected. Surgery is performed through an upper abdominal mid-line incision of 5 cm length. A liver sample is taken for pathological examination and hydroxyproline assay. Subsequently, the jejunal mesenteric vein is uncovered and an incision is made after isolation of a terminal branch of the vein. The distal end of the vein is ligated, and a disposable sterile epidural anesthetic catheter with a sealed tip and three distal side-holes is filled with normal saline containing heparin.
  • the catheter is threaded through the vessel incision into the proximal vein towards the liver, and when sufficient length of catheter is in the vein, it is fixed to the vessel by ligation.
  • the syringe is taken off and the catheter is cut into a suitable length after ensuring the catheter is in the right position.
  • the open end of the catheter is attached to a connector with an injection cap immediately after cut down.
  • the abdominal cavity is closed by suture, and the open end of the catheter with the injection cap filled with heparin saline is embedded subcutaneously.
  • Approximately 1-5 ⁇ 10 7 cells of the donor mouse bone marrow cells (with or without microspheres) or saline are given to the rabbits via portal perfusion by puncturing the injection cap. The perfusion rate was set at about 2-5 ml/min. Rabbits are killed 24 h after the cell administration. Blood samples are taken from the ear margin vein prior to and post perfusion for routine blood, liver function, and renal function tests. After killing, the liver, myocardium, kidney, lung, and brain are sampled and fixed formaldehyde for histological examination.

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